I am Keerthi K Murthy, I have completed post graduation in Physics, with the specialization in the field of solid state physics. I have always consider physics as a fundamental subject which is connected to our daily life. Being a science student I enjoy exploring new things in physics. As a writer my goal is to reach the readers with the simplified manner through my articles.
The drag coefficient is a dimensionless physical quantity influenced by the various parameters that can be affected by the motion in the fluid medium.
In the study of fluid mechanics, the drag coefficient plays a vital role as it resists the motion of the solid object in the fluid medium. This drag coefficient depends on velocity, the object’s cross-sectional area, and density. Is the drag coefficient constant if the parameter mentioned above varies?
We are trying to answer the above equation in this post. Let us discuss how and when is drag coefficient constant and the facts related to the constant drag coefficient below section.
The drag coefficient is directly influenced by the velocity of the flow of the object in the fluid. If the velocity is kept constant over a period, there may be a change in the drag, but the drag coefficient is constant as it is the dimensionless quantity.
CD=2FD/ρv2A
From the above formula, if we consider the object motion in the fluid, the terms FD, ρ, and A are constant for the same object; thus, only possible changes in the velocity we can write the above equation as
CD=Constant/v2
Thus the change in velocity inversely corresponds to the drag coefficient.
The square of the velocity of the object is proportional to the drag coefficient of the object in fluid surroundings. The drag coefficient varies with the square of the relative velocity of the object.
Consider the aerodynamic drag; if the velocity of the object increases to its square value, the drag coefficient falls down at the same value. Thus at a higher velocity, the drag coefficient is less, giving the better performance. So it is clear that increase in velocity, the drag coefficient decreases.
In most cases, the drag coefficient varies with velocity inversely. But other than the velocity, there are several factors responsible for the variation of the drag coefficient. Some of them are listed below:
The angle of object – The factors angle of inclination of the object in the fluid surface is one reason for the variation of the drag coefficient. When the angle of attack is smaller, the drag coefficient is lower.
Variation of drag coefficient with angle
The density of the medium – If the object is low from one medium to another medium of different densities, the drag coefficient varies for the same object. Consider that object is moving from air to water; the density of the air and water is different from one another. Thus the drag force offered to the object changes, thus varying the drag coefficient.
Another necessary consequence of vary in drag coefficient is the type of flow. When the airflow or hydraulic flow is turbulent at a higher velocity, variation in the drag coefficient will occur.
Cross-sectional area –The reference area of the object’s cross-section influences the drag force. If the area of the object is doubled, the drag force is also doubled. Thus varying the drag force causes the proportionate change in the drag coefficient.
D=Aref×constant; where Aref is the area of reference.
When is drag coefficient constant?
In most cases, the constant drag coefficient is referred to as the constant velocity –that means if the velocity of the object on the fluid medium is kept constant, the drag coefficient would also remain constant.
One fact we need to observe here is the Reynolds number of the object motion in the fluid medium is also depends on the entities like speed, density and viscosity of the medium. Thus constant drag coefficient is associated with the terms involved to describe the motion of the body in the fluid environment.
Frequently Asked Questions
What happens when an object possesses a high drag coefficient?
The low or high value of the drag coefficient directly impacts the motion of the object in the fluid.
If an object possesses a higher drag coefficient, the object might be a flat plate whose ability to move in the fluid surface is relatively slow. The object with a high drag coefficient exhibits significant resistance to the motion.
What is meant by Reynolds number?
In fluid mechanics, the Reynolds number describes the flow pattern of the object in different fluids.
Reynolds number can be defined as the dimensionless number given by the ratio of inertial force over the viscous force of the fluid. The Reynolds number helps to categorize the flow of the fluid system as the turbulent, streamlined, or laminar flow.
Can the drag coefficient of a body be greater than 1?
The value of the drag coefficient depends on the nature of the flow such as streamline or turbulent flow.
If two objects of the same area of cross-section move with the same velocity may have different drag coefficients. The drag coefficient for a streamlined body is always less than 1, whereas, for un-streamlined bodies, the drag coefficient value can be 1 or more than 1.
Does the size of the object affect the drag coefficient?
The drag coefficient and the size of the object correlated to one another. Objects of different sizes possess different viscous and inertial forces responsible for the drag force.
The different viscous and inertial force refers to the different Reynolds number; this means that the size of the object refers to a change in the Reynolds number. So it is clear that the size of the object influences the drag coefficient to several extent.
Does the drag coefficient depend on the altitude?
Drag coefficient is independent of the height. The increase or decrease in the altitude does not make any impact on the drag coefficient.
In some cases, as the altitude increases, the Reynolds number may change; thus, there will be a change in the drag coefficient. But if the Reynolds number remain unchanged even if the altitude changes, the drag coefficient is unaffected by the altitude.
The drag coefficient is an essential parameter used to quantify the resistance an object experiences as it moves through a fluid medium, such as air or water. It plays a crucial role in understanding and predicting the aerodynamic behavior of various objects and scenarios. In this blog post, we will explore the definition, importance, factors influencing the drag coefficient, and different methods of calculating it. So, let’s dive in!
Definition and Importance of Drag Coefficient
Image by SchnellGewehr – Wikimedia Commons, Wikimedia Commons, Licensed under CC BY-SA 4.0.
The drag coefficient is a dimensionless quantity that relates the drag force experienced by an object moving through a fluid to the reference area, flow velocity, and fluid density. It is denoted by the symbol Cd and is widely used in the fields of fluid dynamics, aerospace engineering, and automotive design.
The drag force is the resistance force exerted by the fluid on the object in the direction opposite to its motion. It depends on the shape, size, and surface characteristics of the object. By quantifying the drag force through the drag coefficient, engineers and researchers can assess the aerodynamic performance of vehicles, structures, or any object moving through a fluid medium.
The drag coefficient is crucial in determining other aerodynamic properties like the lift-to-drag ratio, which measures the efficiency of an object in generating lift compared to the drag it experiences. A low drag coefficient is desirable as it indicates lower air resistance and improved fuel efficiency, speed, and maneuverability.
Factors Influencing Drag Coefficient
Several factors influence the drag coefficient of an object. Let’s take a look at some of the key factors:
Shape and Surface Characteristics: The shape of an object significantly affects its drag coefficient. Streamlined or aerodynamic shapes, like teardrops, minimize drag by reducing the separation of the fluid flow. Surface roughness, coatings, and protrusions also impact the drag coefficient.
Reynolds Number: The Reynolds number is a dimensionless parameter that characterizes the flow regime around an object. It depends on the flow velocity, object size, and fluid properties. The drag coefficient can vary with the Reynolds number, transitioning between laminar and turbulent flows.
Flow Velocity: Higher flow velocities generally result in higher drag coefficients. As the fluid flow speed increases, the momentum transfer and pressure distribution around the object change, leading to increased drag.
Boundary Layer: The boundary layer is the thin layer of fluid adjacent to the object’s surface. The behavior of the boundary layer, whether laminar or turbulent, affects the drag coefficient. Turbulent boundary layers tend to have higher drag coefficients.
Now that we understand the basics of drag coefficient let’s explore how to calculate it using different software and simulations.
Calculating Drag Coefficient in Different Software and Simulations
How to Calculate Drag Coefficient in Paraview
Paraview is a popular open-source data visualization and analysis software used in various scientific and engineering fields. To calculate the drag coefficient in Paraview, you would typically follow these steps:
Import the simulation results or data representing the fluid flow around the object into Paraview.
Identify a suitable surface on the object for calculating the drag coefficient.
Compute the drag force acting on the surface using the pressure and velocity data from the simulation.
Calculate the reference area, which is the projected area of the surface perpendicular to the flow direction.
Finally, divide the drag force by the product of the fluid density, flow velocity squared, and reference area to obtain the drag coefficient.
How to Calculate Drag Coefficient in CFD
Computational Fluid Dynamics (CFD) is a powerful tool for simulating and analyzing fluid flow and aerodynamic behavior. To calculate the drag coefficient using CFD, you generally follow these steps:
Set up the geometry and boundary conditions of the object and the fluid domain in the CFD software.
Define the flow properties, such as fluid density and viscosity, and the flow velocity.
Run the CFD simulation to solve the governing equations for fluid flow and obtain the pressure and velocity fields.
Identify the surface(s) of interest and extract the relevant data, such as pressure and velocity, from the simulation results.
Calculate the drag force acting on the surface(s) by integrating the pressure distribution along the surface.
Determine the reference area and divide the drag force by the appropriate terms to obtain the drag coefficient.
How to Calculate Drag Coefficient in Solidworks
Solidworks is a widely used 3D computer-aided design (CAD) software that also offers tools for simulating fluid flow and analyzing aerodynamic performance. To calculate the drag coefficient in Solidworks, you would typically follow these steps:
Create or import the 3D model of the object into Solidworks.
Define the fluid properties, such as density and viscosity, and the flow conditions, including velocity and temperature.
Set up the appropriate boundary conditions and mesh the fluid domain.
Run the fluid flow simulation and obtain the pressure and velocity data.
Identify the surface(s) on the object for which you want to calculate the drag coefficient.
Calculate the drag force acting on the surface(s) by integrating the pressure distribution.
Determine the reference area and divide the drag force by the product of fluid density, flow velocity squared, and reference area to obtain the drag coefficient.
How to Calculate Drag Coefficient in Ansys Fluent
Ansys Fluent is a powerful computational fluid dynamics (CFD) software widely used in various industries for simulating and analyzing fluid flow and aerodynamics. To calculate the drag coefficient using Ansys Fluent, you would typically follow these steps:
Set up the geometry and boundary conditions of the object and the fluid domain in Ansys Fluent.
Define the fluid properties, such as density and viscosity, and the flow conditions, including velocity and turbulence model.
Mesh the fluid domain appropriately to capture the flow features and capture the surface details of the object.
Run the CFD simulation and obtain the pressure and velocity fields.
Identify the surface(s) on the object for which you want to calculate the drag coefficient.
Calculate the drag force acting on the surface(s) by integrating the pressure distribution along the surface.
Determine the reference area and divide the drag force by the product of fluid density, flow velocity squared, and reference area to obtain the drag coefficient.
Calculating Drag Coefficient for Different Objects and Scenarios
Now that we have explored different software and simulations, let’s understand how to calculate the drag coefficient for various objects and scenarios.
How to Calculate Drag Coefficient of a Bullet
To calculate the drag coefficient of a bullet, you would typically perform wind tunnel tests or use computational simulations. In wind tunnel tests, the bullet is subjected to controlled airflow, and the drag force is measured. The drag coefficient is then calculated using the same formula we discussed earlier.
How to Calculate Drag Coefficient of an Airfoil
The drag coefficient of an airfoil depends on its shape, angle of attack, and Reynolds number. Wind tunnel tests or computational simulations are commonly used to determine the drag coefficient for different airfoil designs and operating conditions.
How to Calculate Drag Coefficient of a Car
The drag coefficient of a car is of significant importance in automotive design and fuel efficiency. It is typically determined through wind tunnel tests or computational simulations using software like Solidworks or Ansys Fluent.
How to Calculate Drag Coefficient of a Rocket
The drag coefficient of a rocket depends on its shape, size, and flight conditions. Computational simulations using software like CFD are commonly used to calculate the drag coefficient for rockets.
How to Calculate Drag Coefficient of a Parachute
The drag coefficient of a parachute is crucial in understanding its performance during descent. Wind tunnel tests or computational simulations are used to calculate the drag coefficient for different parachute designs.
How to Calculate Drag Coefficient of a Sphere
The drag coefficient of a sphere depends on its size and Reynolds number. It can be calculated through wind tunnel tests or using empirical correlations available for different flow regimes.
How to Calculate Drag Coefficient of a Cylinder
The drag coefficient of a cylinder is influenced by its aspect ratio, surface roughness, and Reynolds number. It can be determined through wind tunnel tests or computational simulations.
Additional Considerations in Drag Coefficient Calculation
Let’s address a few additional considerations when calculating the drag coefficient:
Does Drag Coefficient Change with Size?
Yes, the drag coefficient can vary with the size of the object. It is influenced by the object’s shape and surface characteristics, which can change as the size scales. Therefore, it is essential to consider size effects when analyzing and comparing drag coefficients.
Does Drag Coefficient Have Units?
The drag coefficient is a dimensionless quantity and does not have any units. It is derived from the ratio of the drag force to the product of fluid density, flow velocity squared, and reference area.
How to Calculate Drag Coefficient from Pressure Coefficient
The pressure coefficient is a dimensionless quantity that measures the deviation of the local pressure from the ambient pressure. It is often used to calculate the drag coefficient. The drag coefficient can be obtained by integrating the pressure coefficient along the surface and applying appropriate formulas.
And that concludes our exploration of how to calculate the drag coefficient! We have covered its definition, importance, factors influencing it, different software and simulations, and calculations for various objects and scenarios. Understanding and accurately determining the drag coefficient is crucial for optimizing the performance and efficiency of vehicles, structures, and other objects moving through a fluid medium. Happy calculating!
Numerical Problems on how to calculate drag coefficient
Image by Dmcdysan – Wikimedia Commons, Wikimedia Commons, Licensed under CC BY-SA 4.0.
Problem 1:
A car is moving with a velocity of 25 m/s. The mass of the car is 1200 kg. The frontal area of the car is 2.5 m^2. Calculate the drag force acting on the car. Assume the drag coefficient (Cd) to be 0.35.
Solution:
Given:
Velocity of the car (V) = 25 m/s
Mass of the car (m) = 1200 kg
Frontal area of the car (A) = 2.5 m^2
Drag coefficient (Cd) = 0.35
The drag force (F) can be calculated using the formula:
where:
F = Drag force
Cd = Drag coefficient
ρ = Density of the fluid (air)
A = Frontal area of the object
V = Velocity of the object
Substituting the given values into the formula:
Problem 2:
A ball is thrown horizontally with an initial velocity of 20 m/s. The mass of the ball is 0.5 kg. The drag force acting on the ball is 10 N. Calculate the drag coefficient (Cd). Assume the density of air (ρ) to be 1.2 kg/m^3.
Solution:
Given:
Initial velocity of the ball (V) = 20 m/s
Mass of the ball (m) = 0.5 kg
Drag force (F) = 10 N
Density of air (ρ) = 1.2 kg/m^3
The drag force (F) can be calculated using the formula:
Rearranging the formula, we can solve for the drag coefficient (Cd):
Substituting the given values into the formula:
Problem 3:
A swimmer is swimming in a pool with a velocity of 2 m/s. The mass of the swimmer is 70 kg. The drag force acting on the swimmer is 50 N. Calculate the drag coefficient (Cd). Assume the density of water (ρ) to be 1000 kg/m^3 and the frontal area of the swimmer (A) to be 0.8 m^2.
Solution:
Given:
Velocity of the swimmer (V) = 2 m/s
Mass of the swimmer (m) = 70 kg
Drag force (F) = 50 N
Density of water (ρ) = 1000 kg/m^3
Frontal area of the swimmer (A) = 0.8 m^2
The drag force (F) can be calculated using the formula:
Rearranging the formula, we can solve for the drag coefficient (Cd):
Electrostatic force is a fundamental concept in physics that describes the interaction between charged objects. It plays a crucial role in understanding various phenomena related to static electricity. In this section, we will explore the definition and explanation of electrostatic force, the calculation involved, factors affecting it, and the intriguing concepts of attraction and repulsion.
Definition and Explanation of Electrostatic Force
Electrostatic force, also known as the Coulomb force, is the force of attraction or repulsion between two charged objects. It arises from the interaction between electric charges, which can be positive or negative. Like charges repel each other, while opposite charges attract.
To understand electrostatic force, we need to delve into the concept of electric charge. Electric charge is a fundamental property of matter, and it can exist in two forms: positive and negative. Objects become charged when they gain or lose electrons. The unit of charge is the coulomb (C).
The strength of the electrostatic force between two charged objects depends on the magnitude of the charges and the distance between them. The force follows Coulomb’s law, which states that the force is directly proportional to the product of the charges and inversely proportional to the square of the distance between them.
Calculation of Electrostatic Force
Calculating the electrostatic force between two charged objects involves applying Coulomb’s law. The formula for calculating the electrostatic force (F) is:
F = k * (q1 * q2) / r^2
Where:
– F is the electrostatic force
– k is the electrostatic constant (k = 9 x 10^9 Nm^2/C^2)
– q1 and q2 are the magnitudes of the charges on the two objects
– r is the distance between the centers of the two objects
By plugging in the values for the charges and the distance, we can determine the strength and direction of the electrostatic force.
Factors Affecting Electrostatic Force
Several factors influence the strength of the electrostatic force between charged objects. These factors include:
Magnitude of the charges: The greater the magnitude of the charges, the stronger the electrostatic force.
Distance between the objects: As the distance between the charged objects increases, the electrostatic force decreases. The force follows an inverse square relationship with distance.
Medium between the objects: The presence of a medium between the charged objects can affect the electrostatic force. Different materials have different dielectric constants, which can modify the strength of the force.
Attraction and Repulsion
One of the fascinating aspects of electrostatic force is the phenomenon of attraction and repulsion. When two objects have opposite charges, they experience an attractive force. For example, a positively charged object will attract a negatively charged object.
On the other hand, when two objects have the same charge, they experience a repulsive force. For instance, two positively charged objects will repel each other.
This interplay between attraction and repulsion is responsible for many everyday phenomena, such as the way clothes stick together after being in a dryer or the way a balloon sticks to a wall after being rubbed against hair.
Electrostatic Force Examples
Rubbing the rod with silk clothes
One of the classic examples of electrostatic force can be observed when rubbing a rod with silk clothes. When a rod, such as a glass rod or a plastic rod, is rubbed against a silk cloth, it acquires an electric charge. This happens because the rubbing action transfers electrons from the silk cloth to the rod, causing the rod to become negatively charged while the silk cloth becomes positively charged.
This phenomenon is a result of the transfer of electric charges between two objects. The rod and the silk cloth initially have an equal number of positive and negative charges. However, when they come into contact and are rubbed together, the electrons from the silk cloth are transferred to the rod, causing an imbalance of charges. This creates an attractive force between the negatively charged rod and the positively charged silk cloth.
Television screen
Another example of electrostatic force can be observed when dealing with television screens. Modern televisions, such as LCD or LED screens, are prone to accumulating static charges. This can occur when dust particles or other small objects come into contact with the screen‘s surface.
The accumulation of static charges on the television screen can lead to an annoying phenomenon known as “dust attraction.” The static charges on the screen attract dust particles, causing them to stick to the surface. This can result in a blurry or distorted image, affecting the overall viewing experience.
To prevent this, it is recommended to regularly clean the television screen using a microfiber cloth or an anti-static cleaner. These cleaning methods help to neutralize the static charges and prevent dust particles from sticking to the screen.
Nylon clothes
Nylon clothes can also exhibit electrostatic forces. When wearing nylon clothing, especially in dry conditions, the friction between the fabric and the body can generate static electricity. This can cause the clothes to cling to the body or create a crackling sound when removing them.
The electrostatic forces in nylon clothes occur due to the triboelectric effect, which is the transfer of electric charges between two materials that come into contact and then separate. In the case of nylon clothes, the friction between the fabric and the body causes the transfer of electrons, resulting in an imbalance of charges.
To reduce the effects of static electricity in nylon clothes, one can use anti-static sprays or fabric softeners. These products help to neutralize the charges and prevent the clothes from clinging or generating static shocks.
Photographs sticking to the wrapper
Have you ever noticed how photographs sometimes stick to plastic wrappers or sleeves? This phenomenon can be attributed to electrostatic forces. When photographs are printed, they often acquire a slight electric charge. This charge can cause the photographs to attract and stick to plastic surfaces.
The electrostatic forces at play in this example are similar to those observed when rubbing a rod with silk clothes. The photographs and the plastic wrapper have different charges, resulting in an attractive force between them.
To prevent photographs from sticking to plastic wrappers, one can use anti-static sprays or keep the photographs in acid-free sleeves or albums. These measures help to reduce the accumulation of static charges and minimize the chances of the photographs sticking to the plastic surfaces.
Winter wear
During the winter season, electrostatic forces can become more noticeable, especially when wearing certain types of clothing. Fabrics such as wool, polyester, and synthetic blends tend to generate static electricity due to friction.
When wearing winter wear made from these materials, such as sweaters or jackets, the friction between the fabric and the body can lead to the buildup of static charges. This can result in clothes clinging to the body or causing small electric shocks when touched.
To mitigate the effects of static electricity in winter wear, there are a few simple tricks that can be employed. One option is to use fabric softeners or dryer sheets when laundering the clothes. These products help to reduce static charges and make the fabric less prone to generating static electricity. Another option is to wear a cotton or natural fiber layer underneath the winter wear, as these materials are less likely to generate static charges.
Comb and pieces of paper
The interaction between a comb and pieces of paper is another example of electrostatic forces at work. When a comb is run through dry hair, it becomes charged with static electricity. This charged comb can then attract small pieces of paper, causing them to stick to the comb.
The electrostatic forces in this example are a result of the transfer of charges between the comb and the hair. As the comb is moved through the hair, electrons are transferred from the hair to the comb, causing the comb to become negatively charged. The positively charged pieces of paper are then attracted to the negatively charged comb.
This phenomenon can be demonstrated by running a comb through dry hair and then bringing it close to small pieces of paper. The paper will be attracted to the comb and stick to it, showcasing the effects of electrostatic forces.
Balloons rubbed with hair
Rubbing a balloon against hair and observing the resulting attraction to objects is a classic example of electrostatic forces. When a balloon is rubbed against hair, it acquires a negative charge. This negative charge causes the balloon to be attracted to positively charged objects or surfaces.
The electrostatic forces in this example are similar to those observed when rubbing a rod with silk clothes. The rubbing action transfers electrons from the hair to the balloon, resulting in an imbalance of charges. This creates an attractive force between the negatively charged balloon and the positively charged objects.
This experiment can be easily conducted by rubbing a balloon against hair and then bringing it close to small pieces of paper or a wall. The balloon will be attracted to the objects or stick to the wall, demonstrating the effects of electrostatic forces.
Doorknob
The interaction between a person and a doorknob can also demonstrate the effects of electrostatic forces. When walking on certain types of flooring, such as carpets, friction between the shoes and the floor can generate static electricity. This static charge can then be transferred to the person‘s body.
When the person reaches for a doorknob, the electrostatic forces come into play. The doorknob, being grounded, provides a path for the static charge to discharge. This discharge can sometimes result in a small electric shock, which is the release of the accumulated static charge.
To minimize the chances of experiencing an electric shock when touching a doorknob, one can take a few precautions. Wearing shoes with anti-static soles or using anti-static sprays on carpets can help to reduce the buildup of static charges. Additionally, touching a metal object, such as a key or a coin, before touching the doorknob can provide a discharge path and prevent the shock.
Kid’s hair after sliding over the plastic bouncer house
Have you ever noticed that after sliding down a plastic bouncer house, your kid‘s hair seems to stand on end? This peculiar phenomenon is a result of the interaction between their hair and the plastic surface, which is caused by the fascinating force known as electrostatic force.
J. Rubbing shoes over carpet
To understand why your kid‘s hair becomes electrified after sliding over the plastic bouncer house, let’s explore an example that you might be familiar with: rubbing your shoes over a carpet. When you walk on a carpet, your shoes and the carpet rub against each other, causing the transfer of electric charges.
The friction between the shoes and the carpet leads to the accumulation of electrons on the shoes‘ surface. Electrons are negatively charged particles, and when they build up on an object, that object becomes negatively charged. On the other hand, the carpet loses some of its electrons and becomes positively charged.
Now, when your kid slides down the plastic bouncer house, their hair rubs against the plastic surface. This rubbing action causes a similar transfer of electric charges. The plastic surface becomes negatively charged, while the hair becomes positively charged.
The effects of electrostatic force
The accumulation of opposite charges on the plastic surface and the hair leads to the manifestation of the electrostatic force. This force is responsible for the hair standing on end, as the positively charged hair strands repel each other due to their like charges. This repulsion causes the hair to separate, creating the characteristic “static hair” look.
It’s important to note that the electrostatic force is not limited to hair and plastic surfaces. It is a fundamental force of nature that governs the behavior of charged objects. The electrostatic force is responsible for the attraction and repulsion between charged objects, and it plays a significant role in the study of static electricity.
Exploring the world of electrostatics
Electrostatics, the branch of physics that deals with static electricity, offers a wide range of fascinating examples and applications. Let’s take a quick look at some of them:
Electric charge: The fundamental property of matter that gives rise to the electrostatic force.
Coulomb’s law: The mathematical relationship that describes the force between two charged objects.
Conductors and insulators: Materials that either allow or prevent the flow of electric charges.
Electric field: A region of space around a charged object where the electrostatic force can be felt.
Electric potential: The amount of work needed to move a unit positive charge from one point to another in an electric field.
Electric discharge: The sudden flow of electric charges between two objects with different potentials, often resulting in a spark or a bolt of lightning.
Van de Graaff generator: A device that uses electrostatics to generate high voltages.
Electrophotography: A printing technology that utilizes electrostatic forces to transfer toner onto paper.
Electrostatic precipitator: A device used to remove particulate matter from industrial exhaust gases using electrostatic forces.
Electrostatic painting: A method of applying paint to objects using electrostatic attraction.
Electrostatic motor: A type of motor that uses the electrostatic force to generate motion.
Electrostatic levitation: A technique that uses electrostatic forces to suspend objects in mid-air.
These examples demonstrate the wide-ranging impact of electrostatics in various fields, from everyday life to advanced technologies.
Electrostatic Force and Potential Energy
When it comes to understanding the behavior of charged objects, the concept of electrostatic force plays a crucial role. This force, which arises from the interaction between electric charges, can result in fascinating phenomena and has numerous practical applications. In this section, we will explore some examples of electrostatic force and its connection to potential energy.
Attraction and Repulsion
One of the most fundamental aspects of electrostatic force is its ability to cause attraction or repulsion between charged objects. Like charges repel each other, while opposite charges attract. This behavior can be explained by Coulomb’s law, which states that the magnitude of the electrostatic force between two charged objects is directly proportional to the product of their charges and inversely proportional to the square of the distance between them.
For instance, imagine two positively charged objects placed near each other. As per Coulomb’s law, the electrostatic force between them will be repulsive, causing the objects to push away from each other. On the other hand, if one object is positively charged and the other is negatively charged, they will experience an attractive force, pulling them closer together.
Static Electricity
Static electricity is another fascinating example of electrostatic force in action. It occurs when there is an imbalance of electric charges on the surface of an object. This can happen through various means, such as friction, induction, or contact with another charged object.
When two objects come into contact, electrons can transfer from one object to another, leading to a buildup of charge. For instance, when you rub a balloon against your hair, electrons are transferred from your hair to the balloon, resulting in the balloon becoming negatively charged. This charge imbalance creates an electrostatic force, causing the balloon to stick to surfaces or even make your hair stand on end.
Electric Potential Energy
The concept of potential energy is closely related to electrostatic force. In the context of electrostatics, potential energy refers to the energy stored in a system due to the arrangement of charged objects. It is a measure of the work that can be done by the electrostatic force when the objects are allowed to move.
The formula for electric potential energy is given by:
[PE = \frac{k \cdot q_1 \cdot q_2}{r}]
where (PE) is the electric potential energy, (k) is Coulomb’s constant, (q_1) and (q_2) are the charges of the objects, and (r) is the distance between them.
This formula tells us that the potential energy increases as the charges of the objects increase and decreases as the distance between them increases. When the objects are far apart, the potential energy is low, indicating a stable configuration. However, as the objects move closer together, the potential energy increases, signifying a less stable arrangement.
Understanding the concept of electric potential energy is crucial in various practical applications. For example, it is essential in designing electrical circuits, where the potential energy of charged particles is harnessed to perform useful work.
Comparison with Gravitational and Electric Forces
When discussing electrostatic force examples, it is important to compare them with other fundamental forces, such as gravitational and electric forces. While all three forces play significant roles in our everyday lives, they differ in their nature and effects. Let’s explore the key differences between these forces.
Gravitational Force
Gravitational force is the force of attraction between two objects with mass. It is responsible for keeping our feet on the ground and the planets in their orbits around the sun. Unlike the electrostatic force, which involves charged objects, gravitational force acts on all objects, regardless of their charge.
The strength of the gravitational force depends on the masses of the objects and the distance between them. According to Newton’s law of universal gravitation, the force between two objects is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.
Here are a few examples of the gravitational force in action:
The moon orbiting around the Earth.
A ball falling towards the ground when dropped.
The tides caused by the gravitational pull of the moon and the sun on the Earth‘s oceans.
Electric Force
Electric force, on the other hand, is the force of attraction or repulsion between charged objects. It arises from the presence of electric charge, which can be positive or negative. Like gravitational force, electric force acts over a distance.
The strength of the electric force is determined by the magnitude of the charges and the distance between them. Coulomb’s law describes the relationship between the electric force, the charges, and the distance. It states that the force between two charged objects is directly proportional to the product of their charges and inversely proportional to the square of the distance between them.
Here are some examples of the electric force in action:
The attraction between a positively charged object and a negatively charged object.
The repulsion between two objects with the same charge.
The phenomenon of static electricity, where objects become charged through friction.
Comparison
While both gravitational and electric forces involve the interaction between objects, there are several key differences between them.
Gravitational Force
Electric Force
Acts on all objects, regardless of charge
Acts only on charged objects
Depends on mass and distance
Depends on charge and distance
Always attractive
Can be attractive or repulsive
Weaker compared to electric force
Can be stronger or weaker depending on the charges involved
Plays a significant role in celestial mechanics
Plays a significant role in the behavior of charged particles
By comparing the gravitational and electric forces, we can gain a deeper understanding of the unique characteristics and effects of the electrostatic force. This knowledge is crucial in various fields, including physics, engineering, and everyday life.
Applications and Examples of Electrostatic Force
Electrostatic force is a fascinating phenomenon that has numerous practical applications in our daily lives. From sticking a balloon to a wall to purifying the air we breathe, electrostatic force plays a crucial role in various fields. Let’s explore some interesting examples of how this force is utilized in different applications.
Rubbing a Balloon Against Your Hair and Sticking it to a Wall
One of the most common and fun examples of electrostatic force is when you rub a balloon against your hair and it magically sticks to a wall. This happens because when you rub the balloon, it becomes negatively charged due to the transfer of electrons from your hair. The negatively charged balloon then attracts the positively charged wall, creating an electrostatic force that holds the balloon in place.
Electrostatic Precipitator for Dust Removal
In industries and power plants, dust and pollutants are major concerns. To address this issue, electrostatic precipitators are used. These devices use the principle of electrostatic force to remove dust particles from the air. The polluted air is passed through a series of charged plates, where the dust particles become charged. The charged particles are then attracted to oppositely charged plates, effectively removing them from the air.
Electrophotography or Laser Printing
Ever wondered how laser printers work? Well, electrostatic force plays a crucial role in this technology. In electrophotography, commonly known as laser printing, a photosensitive drum is charged with static electricity. The drum is then exposed to a laser beam, which selectively removes the charge from certain areas, creating an electrostatic image. This image is then transferred to paper using toner particles, which are attracted to the charged areas and fused onto the paper.
Ionizing Air Filters for Air Purification
Air pollution is a growing concern, and electrostatic force is utilized in ionizing air filters to purify the air we breathe. These filters generate ions that attach to airborne particles, such as dust, pollen, and smoke. The charged particles are then attracted to oppositely charged plates or surfaces, effectively removing them from the air. This technology is particularly useful for individuals with allergies or respiratory conditions.
Electrostatic Force in Copy Machines
Copy machines, also known as photocopiers, rely on electrostatic force to create copies of documents. The process involves exposing the original document to light, which creates an electrostatic image on a charged drum. The charged drum attracts toner particles, which are then transferred onto paper and fused to create a copy of the original document. This electrostatic force-based technology revolutionized the way we duplicate documents.
Frequently Asked Questions
What is electrostatic force?
Electrostatic force is a fundamental force of nature that arises from the interaction between electrically charged particles or objects. It is a force that can be either attractive or repulsive, depending on the charges involved. This force is responsible for many everyday phenomena, such as static electricity, where objects become charged due to the transfer of electrons.
What is the law that governs electrostatic force?
The law that governs electrostatic force is known as Coulomb’s law. This law states that the electrostatic force between two charged particles or objects is directly proportional to the product of their charges and inversely proportional to the square of the distance between them. In simple terms, the force increases as the charges increase and decreases as the distance between the charges increases.
Who discovered Coulomb’s law?
Coulomb’s law was discovered by Charles-Augustin de Coulomb, a French physicist, in the late 18th century. Through his experiments, Coulomb was able to establish the mathematical relationship between the electrostatic force, the charges of the objects, and the distance between them. His discoveries laid the foundation for the study of electrostatics and paved the way for further advancements in the field of electromagnetism.
How is the electrostatic force between two charged particles or objects calculated?
The electrostatic force between two charged particles or objects can be calculated using Coulomb’s law. The formula for calculating the electrostatic force is:
F = k * (q1 * q2) / r^2
Where:
– F represents the electrostatic force between the two objects.
– k is the electrostatic constant, which has a value of approximately 9 x 10^9 Nm^2/C^2.
– q1 and q2 are the charges of the two objects.
– r is the distance between the centers of the two objects.
By plugging in the values of the charges and the distance into this formula, one can determine the magnitude and direction of the electrostatic force between the charged objects.
What are charged objects?
Charged objects are objects that have an excess or deficit of electrons, resulting in an imbalance of electric charge. These objects can be either positively charged (having a deficit of electrons) or negatively charged (having an excess of electrons). When two charged objects come into proximity, they can exert electrostatic forces on each other, either attracting or repelling one another based on their charges.
What is the relationship between the electrostatic force and the distance between charged objects?
The relationship between the electrostatic force and the distance between charged objects is inversely proportional. According to Coulomb’s law, as the distance between charged objects increases, the electrostatic force decreases. This means that the force of attraction or repulsion between charged objects weakens as they move farther apart. Conversely, when the distance between charged objects decreases, the electrostatic force becomes stronger.
Can electrostatic force be both attractive and repulsive?
Yes, electrostatic force can be both attractive and repulsive, depending on the charges of the objects involved. Objects with opposite charges, such as a positively charged object and a negatively charged object, will experience an attractive electrostatic force. On the other hand, objects with the same charge, such as two positively charged objects or two negatively charged objects, will experience a repulsive electrostatic force. This behavior is a fundamental characteristic of electrostatic interactions and is governed by Coulomb’s law.
What causes electrostatic force?
Electrostatic force is a fundamental force of nature that plays a significant role in our everyday lives. It is the force that exists between charged particles, and it is responsible for many fascinating phenomena, such as static electricity, lightning, and even the operation of certain devices like Van de Graaff generators. But what exactly causes this force to occur?
The property of charged particles
The creation of electrostatic force is rooted in the property of charged particles. Charged particles, such as electrons and protons, possess an electric charge. This charge can be positive or negative, with opposite charges attracting each other and like charges repelling each other.
When two charged objects are brought close together, the electric charges interact with each other, resulting in the creation of an electrostatic force. This force is governed by Coulomb’s law, which states that the magnitude of the electrostatic force between two charged objects is directly proportional to the product of their charges and inversely proportional to the square of the distance between them.
The role of electric fields
To understand the concept of electrostatic force further, it is essential to consider the role of electric fields. An electric field is a region in which an electric charge experiences a force. It is created by charged objects and can extend throughout space.
When a charged object is placed in an electric field, it experiences a force due to the interaction between its charge and the electric field. This force is the electrostatic force. The strength and direction of the force depend on the magnitude and sign of the charge and the properties of the electric field.
Examples of electrostatic force
Electrostatic force manifests itself in various examples that we encounter in our daily lives. Let’s explore a few of these examples:
Attraction and repulsion: When two charged objects have opposite charges, they experience an attractive electrostatic force. For example, a negatively charged balloon can be attracted to a positively charged wall. On the other hand, when two charged objects have the same charge, they experience a repulsive electrostatic force. This repulsion can be observed when trying to bring two negatively charged balloons close together.
Static electricity: Static electricity is a common example of electrostatic force. It occurs when there is an imbalance of electric charges on the surface of an object. For instance, rubbing a balloon against your hair can transfer electrons, resulting in a buildup of static electricity. This buildup can cause the balloon to stick to your hair due to the electrostatic force of attraction.
Lightning: Lightning is a powerful natural phenomenon that involves the discharge of electrostatic energy. It occurs when there is a buildup of charge in the atmosphere, typically between clouds and the ground or between different regions within a cloud. The discharge of this accumulated charge results in a spectacular display of electrostatic force in the form of lightning bolts.
Van de Graaff generator: A Van de Graaff generator is a device that uses electrostatic force to generate high voltages. It operates by transferring electric charge from a moving belt to a metal dome. The buildup of charge on the dome creates a strong electrostatic force, which can be used for various purposes, such as scientific experiments and demonstrations.
Frequently Asked Questions
Q: What is electrostatic force in chemistry?
A: Electrostatic force in chemistry refers to the attractive or repulsive force between charged objects due to their electric charges. It is a fundamental force that plays a crucial role in various chemical reactions and interactions.
Q: Can you explain electrostatic force with an example?
A: Certainly! An example of electrostatic force is the attraction between a positively charged balloon and a negatively charged wall. The opposite charges on the balloon and wall cause them to be attracted to each other.
Q: What are some examples of electrostatic forces in our daily life?
A: Electrostatic forces can be observed in various everyday situations. Some examples include the attraction between a comb and hair, the repulsion between two like-charged magnets, or the attraction between clothes in a dryer due to static electricity.
Q: How is electrostatic force used in everyday life?
A: Electrostatic force finds applications in numerous everyday activities. It is used in electrostatic painting, where charged paint particles are attracted to a grounded object. Electrostatic precipitators use this force to remove pollutants from industrial exhaust gases. Additionally, electrostatic forces are utilized in electrophotography, which is the technology behind laser printers and photocopiers.
Q: What is Coulomb’s law?
A: Coulomb’s law describes the mathematical relationship between the electrostatic force, the charges of the objects, and the distance between them. It states that the force between two charged objects is directly proportional to the product of their charges and inversely proportional to the square of the distance between them.
Q: Why do electrostatic forces have “static” in their name?
A: Electrostatic forces are called “static” because they are typically observed when charges are not in motion. Unlike dynamic electric currents, electrostatic forces involve stationary or slowly moving charges.
Q: When is electrostatic force maximum?
A: Electrostatic force is maximum when the charges on the objects are large and the distance between them is small. As per Coulomb’s law, increasing the magnitude of the charges or decreasing the distance between them will result in a stronger electrostatic force.
Q: What are some examples of electrostatic force in real life?
A: Electrostatic forces can be observed in various real-life scenarios. Some examples include the attraction between a charged balloon and a wall, the repulsion between two like-charged particles, or the attraction between a charged comb and hair.
Q: How does static electricity force work? Can you provide an example?
A: Static electricity force is a result of an imbalance of electric charges on the surface of objects. For example, when you rub a balloon against your hair, electrons are transferred, leaving the balloon negatively charged. The negatively charged balloon then attracts positively charged hair, resulting in a static electricity force.
Q: Why is electrostatic force stronger than gravitational force?
A: Electrostatic force is stronger than gravitational force because the magnitude of electric charges is much larger than the masses of objects. Additionally, the electrostatic force follows the inverse square law, while gravitational force follows the inverse square of the distance law. As a result, electrostatic forces can be significantly stronger than gravitational forces between charged objects.
When light strikes on a medium, it has to trace a path parallel to the propagation medium or perpendicular to it.
In the previous post, we have given a brief introduction about s polarized waves, which are perpendicular to the direction of propagation.P polarization is the direction of the polarized wave parallel to the propagating medium. Generally, the alignment of the incident wave and the p polarized waves is the same, i.e., both are in the same direction.
Let us discuss how can we achieve p polarization and the cause of p polarized wave in detail.
What is p polarization?
Assume electromagnetic radiation is incident on a dielectric medium such as glass. A part of radiation transmitted through the medium and part of the light reflects due to surface effect, the general polarization process.
Electromagnetic radiation is said to be p polarized when the transmitted radiation is well defined in a single direction parallel to the propagation medium. We can observe the vanishing Brewster’s angle in p polarization.
We know that the transmitted waves are in parallel to the propagating medium; hence the incident wave is also in the exact direction parallel to the medium of propagation.
Light is electromagnetic radiation; hence it can easily undergo polarization when it passes through a polarizing medium.
P Polarized wave
The orientation of the polarized light is characterized to lay parallel to the plane of incidence. The orientation depends on Brewster’s angle as the p polarized light is harder to achieve at Brewster’s angle.
What is p polarized light?
Incident lights are un-polarized; they are randomly distributed in all directions, leading us to the loss of light energy due to certain surface phenomena. To avoid such loss, we use the technique of polarization by bringing the shattered light into one path.
The confinement of the random light into a well-defined direction parallel to the plane of incidence and hence the electric fields are also pointed parallel to the incident plane.
Let us assume that an un-polarized light is randomly distributed on a plane is made to fall on the dielectric medium. As usual, a part gets reflected and partly gets transmitted, resulting in random light radiation tracing a single path. If the interface is perpendicular to the transmitted light direction, the transmitted light traces a path parallel to the propagating medium; this gives the p polarized light.
p polarized wave
We know that all waves cannot undergo polarization; only transverse waves can. One such example of a transverse wave is an electromagnetic wave. Now let us discuss how the p polarization happens in these waves.
Electromagnetic waves combine both electric and magnetic fields laying perpendicular to one another. Since electric fields and magnetic fields are not in phase, we can bring them in phase by polarization. During the process, the unwanted random waves are reflected, and only the waves which can be confined are allowed to transmit. Generally, the p polarization of a wave is referred to as the transverse magnetic polarized wave because, in an electromagnetic wave, magnetic fields are perpendicular to the interface. Hence, they polarized parallel to the meridional plane.
P Polarized Electromagnetic wave
Suppose the electromagnetic wave strikes the medium and get polarized and transmitted through the medium parallel to the plane of incidence, and some of the waves are reflected. The phenomenon takes place between the two mediums of different refractive indices. The tangential component of the electric field and the magnetic field can be resolved as follows;
Let us assume that the electromagnetic wave is transmitting from the medium of refractive index η1 to η2 and θi be the angle of incidence, θr be the angle of reflection and θt be the angle transmission.
Free body diagram describing p polarized EM wave
The tangential component of the electric and magnetic field at the interface of both the medium is
Etan,1 = Etan,2
Htan,1 = Htan,2
For the magnetic field, all the components are tangential, and hence we can write them as
Hi = Hr + Ht
Where Hi is the incident magnetic field, Hr is the reflected magnetic field, and Ht is the transmitted magnetic field.
The tangential vector for the electric field is a bit complicated because all the components are oriented in different directions. They can be written as
Ei cosθi – Er cosθr = Et cosθt
Where Ei, Er and Et are the incidents, reflected, and transmitted electric fields, respectively.
For electric field, the angle of incidence and angle of reflection are same, i.ie., θi=θr; hence the equation can be written as
Ei cosθi – Er cosθi = Et cosθt (1)
The magnetic fields components can be written in terms of electric field as
Ei/η1+Ei/η1=Et/η2 (2)
The ratio of the reflected and transmitted wave with the incident wave gives the required p polarized reflected and transmitted wave as
Er/Ei=r
and Et/Ei = r
Now divide the equations (1) and (2) by Ei we get
Cosθi – r cosθi = t cosθt
1/ηi+r/η1=t/η2
The refractive index can be written in terms of ratio of wave in free space and standard value of refractive index in the medium as
η1=η0/η
Comparing and resolving the equations obtained above we can write the p polarized reflective wave as
rp=η2 cos θi-η1 cos θt/η2 cos θ+η1 cos θt
And the transmitted p polarized wave as
tp=2η2 cos θi/ η2 cos θi+η1 cos θt
The equation obtained above gives the p polarized electromagnetic wave transmitting through a medium. The equations are also called as “Fresnel’s equations for p polarized wave.”
p-polarized incidence
P polarization depends on the wave’s angle of incidence on the interface. As Brewster’s angle vanishes at the interface during the p polarization, the angle of incidence should not be equal to Brewster’s angle.
P polarized waves can be used as an incident wave; this means that p polarized waves are mostly linearly polarized.
If a linearly polarized light wave is incident on the interface of the dielectric medium at Brewster’s angle parallel to the direction of propagating medium, then there would be no reflection taking place on the medium because Brewster’s angle refers to the angle at which no reflection is possible. Hence we can observe complete refraction and transmission of the light wave through the medium when the p polarized wave is used as the incident wave, and thus reflection coefficient will be zero.
p-polarized emission
The emission of the polarized wave is most commonly observed in plasmons. With the help of the photoelectric emission microscope, we can observe the emission of polarized light. The emission of the linearly polarized optical waves is observed in a nanoscale.
Young’s double-slit experiment for high-intensity lasers gives a good account for the p polarized emission. The intensity of the p polarized emission as the function of angle of emission is observed around 597 nm. The electrons with the high energy state emit more rapidly than the lower-energy electrons. For the p polarized emission, the incident p polarized laser should be oblique. The higher energy emitted electrons are accelerated in the polarized direction of the incident laser beam.
P polarized Emission
Can you see circularly polarized light?
Most of us are unaware of our sensitivity towards polarization. Polarization is nothing but the orientation of the light oscillating in a particular direction. We see the pattern of the polarization in the sky, but we cannot recognize them as polarization. Humans can also perceive circularly polarized light with bare eyes.
Human eyes have the ability to detect polarized light. The polarization angle can be detected using a phenomenon called Haidinger’s brushes.
Is p polarization vertical?
Yes, p polarization is vertical. A vertical polarization is corresponds to some arbitrary frame of reference. By considering the direction of gravity, we can say vertical polarization and p polarization are the same.
If we consider the direction of gravity as the propagation medium, then vertically polarized light has the electric field parallel to the direction of the gravity; this means that p polarization is vertical as the polarized wave is parallel to the direction of propagation along with the medium.
However, in some cases the above statement is contradicts what we have assumed. If we choose the propagation of light on the medium considering the gravity direction, p polarization is not vertical, as the electric field is perpendicular to the propagation of the wave.
Thus p polarization is vertical or not depending on the frame of reference. In the laboratory frame we use horizontal direction as the parallel to the propagation.
The frequency of light refers to the number of complete wavelengths that pass a given point in one second. Light is an electromagnetic wave, and its frequency determines its color. But does the frequency of light change with certain factors? Let’s explore this topic further.
Key Takeaways:
Factors
Does the Frequency of Light Change?
Medium
Yes
Doppler Effect
Yes
Gravitational Field
Yes
Temperature
No
Intensity
No
In the table above, we can see that the frequency of light does change with certain factors such as the medium it travels through, the Doppler effect, and the presence of a gravitational field. However, factors like temperature and intensity do not affect the frequency of light.
The Nature of Light
Light is a fascinating phenomenon that plays a crucial role in our everyday lives. It is a form of electromagnetic radiation that allows us to see the world around us. But have you ever wondered about the nature of light? How does it behave? What is it made of? In this section, we will explore the intriguing characteristics of light and delve into its fascinating properties.
Light as a Packet of Energy (Photons)
One of the fundamental concepts in understanding the nature of light is the idea that it can be thought of as a packet of energy called photons. These photons are tiny particles that carry energy and travel at the speed of light. They have no mass but possess both wave-like and particle-like properties. This duality is what makes light so unique and versatile.
The energy and frequency of light are closely associated. Light frequency refers to the number of wave cycles that pass a given point in a second. It is measured in units called hertz (Hz). The frequency of light determines its color, with different frequencies corresponding to different colors of light. For example, red light has a lower frequency than blue light.
How the Energy and Frequency of Light are Associated
The energy of a photon is directly proportional to its frequency. This means that as the frequency of light increases, so does its energy. Conversely, as the frequency decreases, the energy of the light decreases as well. This relationship between energy and frequency is described by the equation E = hf, where E represents energy, h is Planck’s constant, and f is the frequency of light.
Light frequency variation can occur in various situations. For instance, when light passes through different mediums, such as air or water, its frequency can change due to the change in the medium’s refractive index. This phenomenon is known as refraction and is responsible for the bending of light as it travels from one medium to another.
Moreover, the frequency of light can also be affected by temperature. As the temperature of an object increases, the atoms and molecules within it vibrate more vigorously, causing a change in the frequency of the emitted or absorbed light. This phenomenon is known as thermal radiation and is essential in understanding concepts like blackbody radiation.
Another interesting phenomenon related to light frequency is the Doppler effect. This effect occurs when there is relative motion between the source of light and the observer. If the source of light is moving away from the observer, the frequency of the light appears to decrease, resulting in a shift towards the red end of the spectrum, known as redshift. On the other hand, if the source of light is moving towards the observer, the frequency appears to increase, resulting in a shift towards the blue end of the spectrum, known as blueshift.
Understanding the relationship between light frequency and energy is crucial in various scientific fields. It allows us to study the behavior of light across the electromagnetic spectrum, which encompasses a wide range of frequencies and energies. From radio waves to gamma rays, each segment of the spectrum represents a different frequency and energy level of light.
Light and Its Interaction with Different Mediums
Light is a fascinating phenomenon that interacts with various mediums in unique ways. Understanding how light behaves when it encounters different substances is crucial in fields such as physics, optics, and astronomy. In this article, we will explore the ability of light to change its physical properties in different mediums, the processes of refraction and diffraction, the propagation of light through various substances, and the effect of medium on light frequency.
The Ability of Light to Change Its Physical Properties in Different Mediums
When light travels through different mediums, it undergoes changes in its physical properties. These changes are primarily related to the light’s frequency, wavelength, and speed. Light frequency refers to the number of complete oscillations or cycles of the electromagnetic wave that occur in a given time period. It is often associated with the color of light and can vary depending on the medium it passes through.
In some cases, the change in light frequency is caused by the alteration of the medium’s refractive index. Refraction occurs when light passes from one medium to another, causing it to change direction. This change in direction is due to the variation in the speed of light as it travels through different substances. The refractive index of a medium determines how much the light is bent when it enters or exits that medium.
Light Processes: Refraction and Diffraction
Refraction is not the only process that affects the behavior of light in different mediums. Diffraction also plays a significant role. Diffraction refers to the bending or spreading of light waves as they encounter an obstacle or pass through an opening. This phenomenon is most noticeable when light passes through narrow slits or around small objects.
The interaction of light with different mediums can also lead to changes in its wavelength. The wavelength of light is the distance between two consecutive peaks or troughs of the electromagnetic wave. As light passes through a medium, its wavelength can be altered, resulting in a shift in color perception. This phenomenon is known as the Doppler effect in light and is responsible for phenomena like redshift and blueshift.
Propagation of Light through Different Mediums
The propagation of light through different mediums is influenced by various factors, including the temperature of the medium. As the temperature of a substance changes, so does its refractive index, leading to variations in the speed of light. This change in speed can affect the frequency and wavelength of the light passing through the medium.
Moreover, the interaction of light with a medium can also result in changes in its energy. The energy of a photon, the fundamental particle of light, is directly related to its frequency. Therefore, alterations in light frequency can lead to changes in photon energy. This energy change can have significant implications in fields such as spectroscopy and quantum mechanics.
The Effect of Medium on Light Frequency
The medium through which light travels can have a profound impact on its frequency. Light frequency can be shifted due to various factors, including the velocity of the source or observer. This phenomenon, known as frequency shift, is a result of the relative motion between the source or observer and the medium.
Additionally, the presence of gravity can also affect light frequency. According to the theory of general relativity, light passing through a gravitational field experiences a change in frequency. This effect, known as gravitational redshift or blueshift, depends on the strength of the gravitational field.
Frequency of Light: A Closer Look
Light frequency refers to the number of complete oscillations or cycles of a light wave that occur in one second. It is a fundamental property of light and plays a crucial role in various phenomena and applications. In this article, we will delve deeper into the concept of light frequency and explore its behavior under different conditions.
When Does Frequency of Light Change?
The frequency of light can change under certain circumstances. One such instance is when light undergoes a change in wavelength. As we know, wavelength and frequency are inversely proportional to each other. Therefore, if the wavelength of light changes, the frequency will also change accordingly. This phenomenon is known as light frequency variation.
Another factor that can cause a change in light frequency is the speed of light. According to the equation c = λν, where c represents the speed of light, λ denotes the wavelength, and ν represents the frequency, it is evident that if the speed of light alters, the frequency will also be affected. This change in frequency due to a change in the speed of light is often observed in scenarios involving the Doppler effect, such as redshift and blueshift.
Does Frequency Change with Medium?
While the wavelength and velocity of light can be influenced by the medium through which it travels, the frequency of light remains constant. This principle is a fundamental characteristic of light and is governed by the nature of electromagnetic waves. When light passes through different mediums, such as air, water, or glass, it may experience refraction, which causes a change in its velocity and wavelength. However, the frequency of light remains unchanged.
Why Frequency of Light Does Not Change with Medium
To understand why the frequency of light remains constant despite changes in medium, we need to consider the nature of light waves. Light waves are composed of photons, which are packets of energy. The frequency of light determines the energy carried by each photon. When light enters a medium, the photons interact with the atoms or molecules of the medium, causing them to vibrate and re-emit the light. However, the frequency of the re-emitted light remains the same as the original frequency, ensuring that the energy carried by each photon remains constant.
Clarification: While Wavelength and Velocity May Change, the Frequency of Light Remains Constant
It is important to clarify that although the wavelength and velocity of light may change when it passes through different mediums or experiences the Doppler effect, the frequency of light remains constant. This concept is crucial in understanding the behavior of light and its interactions with various phenomena, such as refraction, temperature, and motion.
Practical Examples and Experiments
Examination of the Refraction of White Light on a Prism
One practical example that demonstrates the phenomenon of refraction is the examination of the refraction of white light on a prism. When white light passes through a prism, it undergoes refraction, causing the light to bend and separate into its component colors. This experiment allows us to observe the dispersion of light and understand how different wavelengths of light are refracted at different angles.
To conduct this experiment, we can set up a simple apparatus consisting of a light source, a prism, and a screen. When the white light passes through the prism, it refracts and forms a spectrum of colors on the screen. By measuring the angles at which the different colors appear, we can determine the refractive index of the prism for each color.
This experiment not only helps us understand the refraction of light but also provides insights into the relationship between light frequency variation, change in light frequency, light wavelength, and the speed of light. It allows us to explore the connection between light frequency and the medium through which it travels, as well as the effects of refraction on the alteration of light waves.
How the Refractive Index of the Prism Causes Bending and Dispersion of Light
Another practical example that showcases the impact of the refractive index is the bending and dispersion of light caused by a prism. The refractive index of a material determines how much the light is bent when it enters the material. In the case of a prism, the refractive index varies for different colors of light, leading to the separation of white light into its constituent colors.
The refractive index of a material is influenced by various factors, including temperature, which affects the speed of light in the medium. This experiment allows us to explore the relationship between light frequency and temperature, as well as the Doppler effect in light. By observing the phenomenon of redshift and blueshift, we can gain insights into the frequency shift in light and its connection to energy and the electromagnetic spectrum.
Understanding how the refractive index of a prism causes bending and dispersion of light also helps us comprehend the relationship between light frequency and color. Different colors of light have different frequencies, and as they pass through a prism, they are refracted at different angles, resulting in the separation of colors. This experiment allows us to investigate the alteration of light waves, the refraction index, and their influence on the perception of color.
Frequently Asked Questions
Does the Frequency of Sound Change with the Medium?
Yes, the frequency of sound can change with the medium it travels through. The speed of sound is different in different mediums, and this affects the wavelength and frequency of the sound waves. For example, sound travels faster in solids than in liquids or gases, resulting in a higher frequency.
Is Frequency Independent of the Propagation Medium?
No, frequency is not independent of the propagation medium. The medium through which a wave travels can affect its frequency. Different mediums have different properties that can alter the speed and wavelength of a wave, ultimately impacting its frequency. This is true for both sound waves and light waves.
How are Frequency and Wavelength of Light Related?
The frequency and wavelength of light are inversely related. This means that as the frequency of light increases, its wavelength decreases, and vice versa. This relationship is described by the equation: speed of light = frequency x wavelength. Therefore, if the frequency of light increases, its wavelength will decrease, and if the frequency decreases, the wavelength will increase.
What Factors of Light are Affected by the Change in the Medium?
When light travels through different mediums, several factors can be affected. These include the speed of light, the wavelength of light, and the frequency of light. The speed of light can change depending on the medium, which in turn affects the wavelength and frequency. Additionally, the refractive index of the medium can also impact the behavior of light.
How Does Velocity and Wavelength of Light Change with the Medium?
The velocity and wavelength of light can change when it passes through different mediums. The speed of light is slower in denser mediums, such as water or glass, compared to its speed in a vacuum. As a result, the wavelength of light decreases when it enters a denser medium. However, the frequency of light remains constant.
What is Meant by Light is Quantized?
The conceptthat light is quantized refers to the ideathat light energy is carried in discrete packets called photons. Each photon carries a specific amount of energy, which is directly proportional to the frequency of the light. This quantization of light is a fundamental principle of quantum mechanics and helps explain various phenomena, such as the photoelectric effect.
Does the Frequency of Light Change During Refraction?
No, the frequency of light does not change during refraction. Refraction occurs when light passes from one medium to another and changes direction due to a change in its speed. While the speed and direction of light may change during refraction, the frequency remains constant. However, the wavelength of light can change as it enters a different medium.
What is Refractive Index?
Refractive index is a measure of how much a medium can bend or refract light. It is defined as the ratio of the speed of light in a vacuum to the speed of light in the medium. The refractive index determines how much the direction of light changes when it enters a different medium. Different materials have different refractive indices, which can affect the behavior of light when it interacts with them.
What is Snell’s Law?
Snell’s Law, also known as the law of refraction, describes how light waves change direction when they pass from one medium to another. It explains the relationship between the angles of incidence and refraction, as well as the change in light frequency and wavelength.
When light travels from one medium to another, such as from air to water or from water to glass, it undergoes refraction. Refraction occurs because the speed of light changes as it moves through different materials. The speed of light is slower in denser materials, causing the light waves to bend.
The relationship between the angles of incidence and refraction is governed by Snell’s Law. It states that the ratio of the sine of the angle of incidence to the sine of the angle of refraction is equal to the ratio of the speeds of light in the two media. Mathematically, it can be expressed as:
n₁sinθ₁ = n₂sinθ₂
where n₁ and n₂ are the refractive indices of the two media, and θ₁ and θ₂ are the angles of incidence and refraction, respectively.
Snell’s Law is essential in understanding how light behaves when it passes through different materials. It helps explain phenomena such as the bending of light in a glass prism, the formation of rainbows, and the focusing of light by lenses.
What is Dispersion?
Dispersion refers to the phenomenon where different colors of light separate when passing through a medium. It occurs because the speed of light in a medium depends on its frequency or wavelength.
Light consists of a range of frequencies and wavelengths, which together form the electromagnetic spectrum. Each color of light corresponds to a specific frequency and wavelength. When light enters a medium, such as a prism or a droplet of water, the different colors of light experiencedifferent speeds and angles of refraction.
As a result, the light waves bend at different angles, causing the colors to spread out. This separation of colors is known as dispersion. The colors of the rainbow are a classic example of dispersion, where sunlight is dispersed by water droplets in the atmosphere, creating a beautiful spectrum of colors.
Dispersion is also responsible for various optical effects, such as chromatic aberration in lenses and the creation of colorful patterns in gemstones. It plays a crucial role in fields like spectroscopy, where the analysis of light’s frequency components provides valuable information about the composition of substances.
In addition to the visible spectrum, dispersion can also occur in other parts of the electromagnetic spectrum, such as infrared and ultraviolet light. The amount of dispersion depends on factors like the refractive index of the medium and the change in light frequency.
Dispersion is not only limited to the interaction between light and matter but can also be influenced by other factors. For example, the Doppler effect in light causes a shift in frequency when the source or observer is in motion relative to each other. This effect is responsible for phenomena like redshift and blueshift, which are used to study the motion and properties of celestial objects.
Understanding the principles of dispersion is crucial in various scientific and technological applications. It helps in the design of optical instruments, the development of communication systems, and the study of light’s interaction with matter.
To summarize, Snell’s Law explains how light changes direction when passing through different media, while dispersion describes the separation of colors in light as it interacts with a medium. Both concepts are fundamental in understanding the behavior of light and its interaction with the world around us.
Does the frequency of light change with the medium?
Understanding the impact of frequency is crucial in studying the phenomena of light and its interactions with different mediums. One relevant concept related to this is diffraction, which refers to the bending or spreading of light waves as they encounter an obstacle or pass through a narrow aperture. To explore the intersection between frequency and diffraction, it is necessary to examine how different frequencies of light behave when encountering diffraction. This article on Understanding the impact of frequency delves deeper into this topic and sheds light on the relationship between frequency and the diffraction of light.
Frequently Asked Questions
1. Does the frequency of light change with the medium?
No, the frequency of light does not change when it moves from one medium to another. While the speed and wavelength of light can change depending on the medium, the frequency remains constant because it is determined by the source of the light.
2. Will the frequency of light change when it refracts?
No, the frequency of light does not change during refraction. Although the direction and speed of the light may change as it passes from one medium to another, the frequency remains the same.
3. Why does the frequency of light not change with the medium?
The frequency of light does not change with the medium because it is a property of the light determined by its source. Even though the speed and wavelength of light can change when it enters a different medium, the frequency remains constant.
4. How does the frequency of light change?
The frequency of light can only be changed by altering the source of the light. For instance, changing the energy level of the electrons in an atom can result in the emission of light with a different frequency.
5. Does the frequency of light change when it reflects off a mirror?
No, the frequency of light does not change when it reflects off a mirror. The direction of the light changes, but the frequency remains the same because it is determined by the source of the light.
6. Can you change the frequency of light?
Yes, the frequency of light can be changed by altering the source of the light. This can be achieved by changing the energy level of the electrons in an atom, which can result in the emission of light with a different frequency.
7. How does photoelectric current change with the frequency of light?
The photoelectric current increases with the frequency of light. Higher frequency light has more energy, which can eject more electrons from the surface of a metal, resulting in a higher photoelectric current.
8. When does the frequency of light change?
The frequency of light changes when the energy of the light source changes. This can occur in situations such as an electron moving to a different energy level in an atom, or due to the Doppler effect when the source of light is moving relative to the observer.
9. Does the frequency of light change in different mediums?
No, the frequency of light does not change in different mediums. While the speed and wavelength of light can change when it enters a different medium, the frequency remains constant because it is determined by the source of the light.
10. How does frequency change light and sound?
The frequency of light and sound determines their respective color and pitch. Higher frequencies result in a shift towards the blue end of the spectrum for light and a higher pitch for sound. Conversely, lower frequencies result in a shift towards the red end of the spectrum for light and a lower pitch for sound.
Polarization is the process of aligning the unpolarized electromagnetic wave in one direction. This process of alignment into a single direction corresponds to the nature of the incident wave on the medium.
Based on the nature of the incident wave striking the medium, the polarization of the wave can be said to s polarized or not. The propagation of an s polarized wave is the same as the normal polarized wave, but the incidence of the wave on the medium makes the wave classified as s-polarized. A brief introduction to s-polarized waves is discussed in this post.
What is s polarized light?
If a shattered electromagnetic wave, say the light wave, is made to transmit through a plane medium, the light is confined into a single direction.
When the incident light is in the direction perpendicular to the plane of propagating medium, and then it confines the light wave to achieve a single direction of propagation, such a polarization of light is called s polarized light.
Illustration of s polarized light
Suppose an unpolarized light wave is an incident on a dielectric medium; after transmitting in the medium, the incident light wave traces a well-defined path in a single direction, causing the polarization if the polarization takes place perpendicular to the medium the polarization nothing but s polarization.
The light which has to be s polarized should be perpendicular to the plane of incidence and parallel to the interference.
If the incident light is monochromatic, the state of polarization of light involves the non-zeros components at the planar interface generates the field in the rarer medium whose polarization will be elliptical.
s-polarized light reflection
When the light gets polarized, not all the waves of light are transmitted through the medium. Some of the light waves may be reflected by the plane medium.
The reflection of s polarized light depends on Brewster’s angle as the incident angle. The s polarized light undergoes total internal reflection (TIR) at a dielectric interface at the angle of incidence ψ. Since at Brewster’s angle, no reflection takes place, the angle of incidence must be less or greater than Brewster’s angle.
For expected propagation of incident light perpendicular to the interface of the medium, the s polarized light shows reflectivity. The s polarized light component is not perpendicular to the electric field components; thus, light propagating with Brewster’s angle must undergo total internal reflection.
Gauss law states that “the electric field must be continuous except in the presence of charge.” But for s polarized light, the electric field in the incident and transmitted layers is not equal. Thus electric field shows discontinuity, so there will be the reflection of s polarized light due to the exhibiting the different amplitudes of the electric field in the transmission medium.
Figure illustrating s polarized light reflection
The formula can give the angle of reflection of s polarized light
tanθp=n2/n1
Where θp is the reflected angle and n1, and n2 is the refractive indices of the medium, since the transmission of polarized light is taking place from one medium to another medium.
The equation can also be written as
sinθp/cosθp=n2/n1
Since the above equation is similar to Snell’s law, it can be rewritten as
sinθp/sinr=n2/n1
Because cos θp = sin r, the angle of reflection. Thus we get the equation as
sin π/2-θp=sinr
θp+r= π/2
The above equation gives the reflection of the s polarized light.
s-polarized incident light
If the linear polarization of incident light itself s polarized then the polarized, then there will be the complete transmission of the light through the medium.
When the s polarized light is incident on the dielectric medium, the refraction of the polarized light can be observed. The incident light refracts into two beams. One refracted beam is oriented parallel to the transmission medium, and another one is perpendicular to the transmission medium.
Thus we can use the polarized filter to block the two refracted rays to produce the image. The light is entirely blocked by the polarized filter producing the bright image of the perpendicular component, and the second image will appear when the filter is turned 90°.
s polarized wave
The term polarization is possible only in electromagnetic waves and radio waves. Since, in the case of an electromagnetic wave, the electric field and the magnetic field are oriented in different directions perpendicularly, the polarization can be easily monitored.
S polarized electromagnetic wave
In this section, let us learn what is s polarized wave and the nature of s polarized wave.
What is s polarized wave?
Since we are talking about the wave, we will consider the electromagnetic wave because the electromagnetic wave is an excellent example of the transverse wave. The electromagnetic wave incident on the medium is confined into a single direction, i.e., both electric field and magnetic field, causing the polarization.
If the electromagnetic field hits the medium and it begins transverse perpendicular to the plane of incidence, then the wave is said to be s polarized wave. The amplitude of the wave increases with the angle of incidence increases in the s polarized wave.
Suppose an electromagnetic wave of E and B field is incident on the plane medium, a part of the wave is transmitted, and a part of the wave is reflected in the same medium as shown in the figure.
The electric field vector for the above oscillation of the electric field is given by
E→=x→ A sin (wt – kz)
Where; A is the amplitude of the wave and k is the propagation vector.
The electric field vector is perpendicular to the plane of incidence; thus, the polarized wave is called an s polarized wave. The propagation vector has three components KI, Kr, KT; these are the propagation vectors of the angle of incidence, reflection and transmission of the s polarized wave.
s-polarized dipole
When a minimal distance holds two equal and opposite charges, the arrangement is called a dipole. Suppose a dielectric material is kept on an electric field; the field induces the electric dipole and holds them in the direction of the field. The external electric field is also involved in the process of aligning the electric dipole in the field direction; this entire process is called dipole polarization.
When the electric dipole induced by the field is perpendicular to the plane of propagation, then the polarization is known as s polarized dipole. In this case, polarizability, the negatively charged particles are slightly moved away from the positively charged particle so that the molecule acquires an electric dipole moment.
Frequently Asked Questions
Does s polarized lights are linearly polarized?
The light is linearly polarized when the electric field of light is restricted to propagate in a single direction along the plane of propagation.
If the s polarized light is allowed to move only in the direction of propagation without the phase shift, then the s polarized lights are said to be linearly polarized. Generally, if the incident light wave and the transmitted light waves are in phase, perpendicular to the propagation plane are linearly s polarized light.
Can we get circularly s polarized light?
The circularly polarized lights have the 90° phase shift with the incident light-medium.
If the polarized light is out of phase at 90° and propagates normal to the plane of incidence, then we get the circularly polarized light as a component of s polarized light. The magnitude and the amplitude of the polarized light are equal with the incident light; only there will be a shift in the phase of the polarized light.
Does laser beams are polarized?
Most of the laser beams are polarized, but some of the lasers are un-polarized. It depends on the nature of designing the optics of the laser source.
Laser beams are confined to a single direction and are coherent. Point them on the white paper in a dark room if you have a laser. Rotate the paper; if the brightness of the laser spot changes, then the laser source is partially polarized. If the brightness remains the same, the laser beams are almost polarized. It isn’t easy to achieve an utterly polarized laser.
Can we achieve complete transmission of incident light by polarization?
Due to some surface phenomena, the complete transmission of incident light through polarization is hard to achieve.
Polarization refers to holding up randomly distributed light waves in one single direction. The confinement of all the light rays which strikes the medium is not possible becomes some of the light rays may get reflected from the medium before they get confined.
What are the methods used for polarizing the light?
Generally, there are four methods used to polarize the unpolarized light, which used a specific medium to execute their action; they are
Polarization by Polaroid filters -uses particular dichroic material that absorbs the unwanted unpolarized lightwave and transmits only the suitable light rays.
Polarization by reflection –they use the non-metallic medium to prevent un-polarized light propagation from confining them.
Polarization by refraction – they use two material mediums of different refractive indices for polarizing the shattered light.
Polarization by scattering – involves the propagation of un-polarized light to travel on through a medium that can absorb and reemit light.
A wave can undergo many phenomena such as reflection, refraction, diffraction, and dispersion, which you already know from our previous articles. One among such wave phenomena is polarization.
Polarization is the property of the electromagnetic wave that confines the shattered waves into a single direction. The polarization is further classified into s-polarized and p-polarized by considering the behavior of waves on the plane of propagation. This post is concerned with a comparative analysis of s polarized vs p polarized wave.
Comparison of s polarized vs p polarized wave
Not all wave has the ability to undergo polarization. There are some restrictions for the wave to undergo polarization; such properties are discussed in the table below, giving a brief comparison of s polarized vs p polarized wave.
S polarized
P polarized
Definition
When electromagnetic radiation is incident on a plane medium, the polarization of radiation will occur perpendicular to the plane of incidence; such polarization is called as s polarized.
When an electromagnetic radiation incident on a plane medium, the polarization of the radiation occurs parallel to the plane of incidence, such polarization is called p polarized.
Nature of angle of incidence
In most cases, when an incident wave is made to fall on the polarizer at an angle equal to Brewster’s angle, one can achieve an s-polarized wave.
At Brewster’s angle, we cannot achieve the p polarized wave. The angle of incidence must be greater or less than Brewster’s angle.
Variation of Brewster’s angle
The Brewster’s angle does not affect by the s-polarization; it remains as usual with the incident wave.
The Brewster’s angle vanishes as the wave incident on the plane medium
Reflective ability
As the angle of incidence increases, the ability to reflect the wave also increases in s polarized wave.
There will be no reflection occurring at Brewster’s angle. Almost up to 90°, the reflection is less. As the angle incidence increases above 90°, the reflective ability slightly increases.
Phase difference
There will always be a 180° phase shift of the polarized wave with the incident wave, Brewster’s angle does not matter for the phase difference in s polarized wave.
In the case of a p polarized wave above Brewster’s angle, the phase difference can be seen in a p polarized wave. There will be a 180° phase shift with the incident wave, but below the Brewster’s, the polarized wave is in phase with the incident wave.
The amplitude of the reflected wave
The amplitude of the reflected wave increases with the incidence angle in s polarized wave.
In the case of a p polarized wave also the amplitude of the reflected ray gradually increases with the angle of incidence.
Comparative analysis of s polarized vs p polarized wave
Free body diagram illustrating s polarized vs p polarized wave
Facts to be remember
S polarized, and P polarized waves are essential properties for the reflection and transmission of waves in the medium.
The terms s and prefers to their alignment in the medium. S refers to Senkrecht, which is derived from the German word that means perpendicular or normal, whereas P refers to parallel, based on the alignment of wave incident on the medium.
In the diffraction grating, the s polarized wave refers to the perpendicular polarization with respect to the lines on the grating, not to the perpendicular to the plane of incidence.
If you consider the prism of Brewster’s angle, the reflected ray staying in the horizontal direction is considered to be s polarized because if you tilt the prism, the reflected rays go upward, but it does not change.
The nature of polarization as s polarized and p polarized is considered according to the direction polarization with respect to the plane of incidence. Thus s and p polarized waves must be relevant to the plane of incidence.
Frequently asked questions
What is meant by polarization?
When a wave undergoes any phenomena such as reflection, refraction, diffraction, etc., the waves can propagate in any direction. These waves have not bounded to propagate in a particular direction.
Polarization is the process applied to the waves to bring all the scattered waves in a single proper direction. The longitudinal waves cannot undergo polarization; only the transverse wave can be polarized. The polarization involves the transverse waves to specify the geometrical orientation.
What are the conditions required for polarization?
A wave has to possess several properties to undergo polarization. Some of such conditions are listed below.
A wave should be a transverse wave to undergo polarization.
The wave must be coherent, and the phase difference of the incident wave should be constant.
The medium of propagation should be homogenous.
The wave should be perpendicular to the direction of propagation.
Can sound waves undergo polarization?
We have understood that only transverse waves can undergo polarisation from the definition of polarization. However, the sound wave is a longitudinal wave; it cannot undergo polarization.
Sound waves cannot undergo polarization because the sound wave vibrates only in a single direction, along the direction of propagation. Thus it becomes quite difficult to confine the wave. Hence sound waves cannot be polarized.
An only transverse waves can undergo polarization; explain why?
A wave is said to be transverse when the wave oscillates along the path at a right angle to the direction of propagation.
The transverse wave can vibrate in the direction perpendicular to the energy level so that vibration can occur in all the perpendicular directions, and it becomes easy to confine them. So for transverse waves, there could be two orthogonal directions for propagation in three-dimensional space.
What is meant by Brewster’s angle?
When a light incident on a transparent dielectric medium, the maximum amount of light get polarized at a certain angle, that angle of incidence is nothing but Brewster’s angle.
Brewster’s angle is more precisely stated as it is an angle of incidence at which the wave can perfectly transmit along the transparent surface without letting back reflection of the wave so that one can get the maximum amount of polarized wave.
Linearly polarized wave – the wave is restricted to a single plane along the direction of wave propagation.
Circularly polarized wave – the wave has two linear components perpendicular to each other. Their amplitudes are equal with a phase difference of π/2, resulting in the circular motion of the polarized wave.
Elliptically polarized wave – the wave has two linear components whose amplitudes and phase differences are unequal, resulting in the elliptical motion of the polarized wave
Frequency refers to the number of waves passing towards a fixed point in a unit of time. Since diffraction occurs due to the wave striking the corner of the obstacle, does frequency affect diffraction as the wave has a certain frequency? If yes, then let’s learn the relation between frequency and diffraction and how does frequency affect diffraction in detail.
How does frequency affect diffraction?
Every wave propagating in a medium has a certain frequency that is inversely associated with the wavelength. However, we have learnt the influence of wavelength on diffraction; it is so obvious that frequency can also affect the diffraction.
Diffraction pattern of wave illustrating how does frequency affect diffractionImage credits: Image by PublicDomainPictures from Pixabay
Frequency is an invariable entity after the diffraction, i.e., the frequency of the incident wave does not change when the wave gets diffracted. However, the amount of diffraction depends on the frequency of the incident wave.
Diagram illustrating How does frequency affect diffraction
The wave with high frequency diffracts less than the wave with low frequency.
Since high frequency refers to shorter wavelength, in the phenomena of diffraction, always wave with greater wavelength diffract more rapidly than the short wavelength. Thus, the incident wave with low frequency must be incident to achieve greater diffraction.
If we consider the example of the sound wave, the following facts can be observed:
When a high-frequency sound wave with a shorter wavelength strikes the obstacle, the waves do not diffract; instead, they reflect back around the obstacle, creating the shadow of sound behind the obstacle.
The low-frequency sound strikes the obstacle; the wavelength of the incident wave is much longer than the barrier; thus, the wave can easily pass over the corner of the barrier, creating the wave’s diffraction.
When a wave of frequency equal to the barrier dimension strikes, they create the mid-frequency range, and the waves are diffracted around the object. The edge of the object is used as the focal point and generates the new wave front whose frequency will remain the same, but the intensity is reduced.
Frequency and diffraction relationship
Though the frequency of the wave and diffracted wave remains the same before and after the diffraction occurs, diffraction always depends on the frequency. This dependency can be expressed by providing the relation between the frequency and diffraction as given below.
Let us suppose that a light wave of wavelength λ is passed through a slit of width d and the light wave s travels in a straight line to give the diffraction fringes.
Image to describe the relation between frequency and diffraction
The amount of diffraction can be given by the equation,
sinθ=λ/d
Where; θ is the angle between the incident and diffracted wave.
The wavelength can be given in terms of frequency as
f=c/λ
Where; c is the velocity of light. Rearranging the terms, we get frequency as
λ=c/f
Replacing the λ in the above equation; we get
sinθ=c/df
If we have considered the aperture as a circular aperture, the equation can be modified as
sinθ=1.22(c/df)
Where; 1.22 is the constant d is the diameter of the aperture and θ is the angle between the incident and diffracted wave.
If the angle θ is very small; then, sinθ~θ , then the equation will be
θ=1.22(c/df)
This gives the diffraction of the wave with a certain frequency of the incident wave. This gives the relation between the diffraction and frequency as they are inversely related. The equation we have obtained says that the diffraction is more if a wave of low frequency is incident on the aperture.
Frequently Asked Questions
What are the essential conditions needed for the diffraction of light?
The light undergoes diffraction if it possesses the conditions that are listed below.
The wavelength of the light should match the width of the aperture used.
The width of the slit should be sufficiently narrow to get good diffraction fringes.
Does diffraction cause interference?
Yes, in some cases, the diffraction can cause interference.
Interference refers to the superposition of two or more coherent light waves. If a monochromatic light wave is passed through a double slit, first they get diffracted at the corner of the slit, and then the two diffracted light waves superimpose on one another, causing the interference.
Are the fringes obtained from diffraction equally spaced?
The spatial arrangement of the fringes depends on the slit we have chosen for the diffraction experiment.
In a single slit experiment, the fringes are not equally distributed. The width of the fringes we have obtained from the single slit is unequal, and its width decreases as it moves outward.
In a double-slit experiment, the fringes are equally spaced as we get interference of the diffracted light; their width is also equal.
Does the angle of the incident wave affect the diffraction?
The angle of incidence does not affect the diffraction of the wave.
Diffraction is a wave phenomenon that depends on the wavelength, frequency of the wave and the linear dimension of the hurdle. The angle at which the wave has incident does not matter for the wave to get diffracted.
Do the properties of the wave remain the same after the diffraction?
Diffraction is the process that does not change any properties of the wave. It slightly changes the direction of the wave.
When a wave of specific wavelength, frequency, and speed strike an obstacle, the wave changes its direction, causing the bending of the wave. The properties like speed, wavelength, frequency and time period remain unaltered even after the diffraction.
How does the refractive index of the medium affect the diffraction?
Diffraction is a spatial phenomenon that occurs due to the invariant properties of the wave medium.
The wavelength of the wave inversely varies with the refractive index of the medium, i.e., the medium which possesses a high refractive index, the wave travelling in the medium should possess a shorter wavelength—the shorter wavelength results in less thus high refractive index medium exhibit low diffraction.
In optics, the study of diffraction and dispersion helps us understand the behavior of light, such as the bending and spreading of light when it passes through a medium.
The light wave has the ability to bend and then spread out itself; this behavior of light can be distinguished as diffraction and dispersion. Both terms sound similar, but there are certain natures that differ them from one another. In this post, we give a brief comparison of diffraction vs dispersion of light and their behavior.
Comparison of Diffraction vs Dispersion
The table given below helps you to understand the differences and also similarities between diffraction vs dispersion.
Diffraction
Dispersion
Definition
When the light strikes the edge of the hurdle, it bends at the corner, creating the geometrical fringes.
The propagation of light waves from one medium to another medium of different refractive indices splits into different wavelengths.
Dependency on wavelength
Diffraction depends on the wavelength of the incident light, as if the light wave of longer wavelength is incident on the slit, it diffracts more.
The spreading up of light waves depends on their wavelength. The light with a shorter wavelength disperse first, and then, in increasing order, they spread out of the medium.
The velocity of the light
The velocity of the light before and after diffraction of light remains constant, i.e., diffraction does not affect the velocity.
There will be a change in the velocity of the incident light as the light is travelling between the two mediums of different refractive indices.
Monochromaticity
The diffraction can be obtained using both monochromatic and polychromatic light. We get diffraction fringes of seven colors in the polychromatic, i.e., using white light and fringes of dark and bright by using the monochromatic light.
Dispersion can be achieved only by using white light or polychromatic light. We do not see the dispersion of waves in monochromatic light.
Dependency on the angle of deviation
Diffraction is independent of the angle of deviation of the light if the monochromatic light is used for the diffraction process. If we are using white light for the diffraction process, it depends on the angle of deviation.
Dispersion entirely depends on the angle of minimum deviation.
Refractive indices of the mediumSincediffraction depends on the wavelength and frequency of the incident light, which depends on the refractive index of the medium, thus diffraction also depends on the refractive indices of the medium of propagation.
The Refractive index of the propagating medium is the leading cause of the dispersion. The dispersion of the light takes place when the light travels from a denser medium to a rarer medium or vice versa of different refractive indices.
Examples
A diffraction grating is the best example of the diffraction of white light. Holograms and CD which reflects the rainbow colors are due to diffraction
When white light travels through the prism, the white light disperses into seven colors of a different wavelength. The formation of a rainbow is also an example of dispersion.
Comparison of diffraction vs dispersion
Image to illustrate comparison of diffraction vs dispersion
Some interesting points to remember
Not only light the sound waves can also undergo diffraction as well as dispersion. The diffraction of sound is already discussed in the previous article. The dispersion of sound waves is called acoustic dispersion, in which sounds of different frequencies are separated when a sound wave is passed through a certain medium.
In some cases, a diffracted light can be dispersed, i.e., when a narrow slit diffracts white light on a grating, the diffracted light is then dispersed into its prominent colors. For example, on the CD, we see the diffraction pattern that disperses into all the prominent colors of the rainbow.
The reason for dispersion is refraction. When the white light is refracted by a glass prism, we obtain the dispersion of colors of various wavelengths. For example, when the rainbow is formed, we see the seven colors, which are separated accordingly by their wavelength; the white light is first refracted, then dispersed into the colors of the rainbow.
From the study of diffraction vs dispersion, we know that dispersion is related to both diffraction and refraction, depending on the medium of propagation and the nature of the incident light.
Frequently asked questions
What is meant by angle of deviation?
When a wave passes from one medium to another, the wave may bend, making a certain angle θ. The bent wave that emerges out of the medium is called refracted or diffracted wave.
The incident wave deviated its direction when it propagated between two mediums or slits. The angle between the incident wave and the deviated wave is called the angle of deviation. The angle of deviation on the wavelength of the emerging wave. The angle of deviation can also be given by taking the difference between the angle of the incident wave and the angle of the emerging wave.
How do diffraction and dispersion are related?
If we are talking about white light, then diffraction and dispersion are related.
When white light is passed through a narrow slit, and it is made to an incident on the grating, then we can observe the diffraction pattern on the grating. The diffraction pattern obtained by the grating is the dispersed colours of different wavelengths of light. Thus diffraction is related to dispersion splitting the white light into individual wavelengths.
Does the frequency of wave change during dispersion?
The dispersion is a property of the wave which depends on the speed as well as wavelength. Since wavelength is inversely related to frequency, the dispersion also depends on the frequency.
The shape of the wave pulse changes as it travels from one medium to another medium of dissimilar refractive indices, this change in the shape leads to the change in the velocity of the wave phase, which depends on the frequency. Thus any medium acts as a dispersive medium; there will be a regular change in the frequency.
The dispersion of light can be seen in a prism, not on a glass slab; why?
Even though the glass slab has the ability to refract the incident light, it does not have the ability to disperse the incident light is due to its geometrical structure.
A glass slab is designed with two parallel interfaces, which refracts the incident light and then emerges out of the slab parallel to the incident light; also, they are so closely spaced that splitting up of light would be difficult. However, in the case of a prism, the refractive interfaces are not parallel, and there is a sufficient gap to separate the colors into the desired wavelength.
The behavior of waves traveling from one medium to another medium is different. The difference in the behavior of waves gives the phenomena of diffraction and refraction.
Diffraction and refraction are the processes of change in the direction of the wave. Both the light and sound waves can undergo diffraction and refraction. In this post, we will learn the differences between diffraction vs refraction in both light and sound and learn various facts involved in diffraction vs refraction.
Diffraction vs refraction of light
The comparative analysis of diffraction vs refraction briefly summarizes the nature of propagation light waves in the various mediums. In this section, let us discuss the comparison of diffraction vs refraction of light.
Diffraction
Refraction
Definition
Diffraction is the bending of light at the corner of the hurdle when the light ray passes through the slit giving geometrical shadow.
Refraction is the bending of light when it travels from one medium to another of different refractive indices.
Wavelength
The diffraction corresponds to the wavelength; as the wavelength is more, the amount of diffraction will be more.
Image demonstrating the comparison of diffraction vs refraction of light wave
Diffraction vs refraction sound
The change in the direction of the sound wave can produce diffraction as well as refraction depending on the nature of the medium and material. The differences between acoustic diffraction vs refraction is listed as follows:
Diffraction
Refraction
Definition
The diffraction of sound waves involves a single medium where the bending of the sound wave takes place, and then the sound wave spreads out.
The refraction of the sound waves involves the bending and spreading of the wave, and hence the speed of the sound wave changes. The speed may increase or decrease depending on the nature of the medium.
TemperatureThe diffraction of sound waves is generally a temperature-independent phenomenon.
The refraction of sound waves generates a natural temperature gradient for the atmosphere.
Wavelength
The wavelength of the sound wave plays a vital role in the diffraction of sound. The greater wavelength sound wave diffracts more than, the shorter wavelength wave.
If the wavelength is shorter, the frequency will be high; this makes the sound wave attain a higher pitch, and thus the refraction will be greater.
Size of the passage
The size of the passage contributes to the diffraction. The diffraction of the sound wave is more if the passage is smaller.
Since the refraction of a sound wave is caused by traveling from one medium to another, the size of the passage or medium does not matter; the only thing that matters how dense the medium is.
The velocity of the wave
The velocity of the sound wave remains the same before and after the diffraction.
Refraction is caused due to change in direction, and thus, the velocity also changes when the refraction of a sound wave happens.
Examples
Forest-dwelling birds hear the sound of other birds in the long-distance is due to the diffraction of the sound wave at the edge of the trees.
Diffraction and refraction are very important properties of the wave where bending or spreading of the wave occurs. These are natural phenomena that can be observed everywhere around us. Though both properties encounter bending phenomena, they differ from one another.
Refraction is a bulk phenomenon; it occurs when the wave hits a surface and travels through the bulk of another medium of different densities, and the bending of the wave takes place. While the diffraction is an edge phenomenon, where the wave hits the corner of the obstacle, which is placed in the path of the propagation of the wave, and then bending or spreading of the wave takes place.
Though both diffraction and refraction are the characteristics of the wave, their result is also different as the refraction produces the visual image, whereas the diffraction produces the fringes or geometrical shadows.
Is it a rainbow diffraction or refraction?
Rainbow is a naturally occurring process in the sky when the light ray from the sun passes through the water droplet.
Even though the rainbow looks like the cause of diffraction as the water droplet acts as a grating because water is a transparent medium, diffraction does not play any role in the rainbow formation. As the light ray travels from the water droplet to air, there is a change in the light ray’s propagation medium. The refractive indices of air and water are different. As the water medium is denser than the air medium, there will be refraction, not diffraction.
The cause of the rainbow is due to the refraction, and reflection also plays a part in causing the rainbow. When the light ray enters the water droplet, the ray gets reflected inside the droplet more than once; this is called total internal reflection, which causes the rainbow to look shiner. When the ray leaves the droplet, the rays are double refracted, and they disperse into a cone of seven constituent colors of various wavelengths.
Is a prism refraction or diffraction?
The prism has the ability to disperse the white light into its constituent colors when white light is passed through the prism. The dispersion of white light in the prism is due to refraction, not diffraction.
When the white light ray is encountered on the prism, the bending of the light ray takes place at the surface of the prism. Since prism is made up of a particular type of glass-like material, the refractive index of the prism is more than the air; the splitting up of colors takes place inside the prism of a different wavelength.
The spectrum we obtained from the prism of different frequencies is not the diffraction pattern. Prism is refraction, not diffraction.
Each spectral line emerges out of the prism, and the rainbow has a different wavelength in the order of red, yellow, green, blue-green, blue, and violet. Red has the longest wavelength, and violet has the minimum wavelength.
Some interesting facts of diffraction and refraction
Not only light and sound waves, electromagnetic can also undergo refraction and diffraction.
The amplitude of the wave decreases after the refraction and diffraction, as there is a change in the direction of the wave; hence during the process, some amount of energy may get lost; as a result, there will be an amplitude decrease.
Water can undergo both refraction and diffraction as it is a transparent medium. For example, if we place a straw in a glass of water, it looks like the straw is cut off; in this case, water acts as a refractive medium. While if a light wave hits the island and bends, it produces the shadow of the island due to diffraction.
On the earth, we can able to visualize maximum of ¾th of the rainbow cone; a pilot can visualize the complete rainbow.
