The article discusses is volume an extensive property – equivalent to the amount of matter.
The volume estimates the amount of space occupied by any object. In comparison, the mass estimates an object’s amount of matter. Hence, the mass and volume, physical quantities, are extensive properties of matter, dependent on each other and easily measured.
The physical quantities are categorized into two properties: intensive and extensive. When a quantity is independent of the other quantity or does not alter its values, it is ‘intensive property‘. Quantities like melting point, freezing point, boiling point, odor, ductility, color, conductivity, luster are intensive properties with a fixed value.
When the value of the quantity is dependent on the size of an object, it is ‘extensive property’.
Is Volume an Extensive Property
How to Categories Physical Quantities of Matter? (credit: shutterstock)
When we narrate that a container has a capacity of five liters, it signifies that it can store five liters of matter within. Since the measuring unit of volume quantity is Liter (L), it depicts how much matter any object possesses.
Volume as an Extensive Property
Suppose another container of the exact material has a capacity of eight liters, then we can convey that a container with eight liters that have better volume than container with five liters.
The volume is an extensive property as it varies with an object’s capacity.
The volume of any object is its capacity to keep the matter. So volume varies either when the capacity of the object changes or the amount of matter within the object changes. It implies that water is dependent on the object’s size, and hence, it is categorized as extensive property.
Suppose we have to calculate the identical water volume into different storing objects, such as a spoon and a jar. Both object’s capacity to keep the water is different. The spoon holds about 5ml of water, and the jar has about 250ml of water. Consequently, the volume of water is distinct in both objects.
How is Volume an Extensive Property?
If we expect to calculate the amount of matter within the water or, simply say, the mass of water into both objects, we obtain different mass values. That’s depicts volume and mass quantities are directly related to each other. The larger the matter, the larger its volume and mass.
If we split the system into the ‘n’ number of a subsystem, the value of physical quantities for the system would be the sum of the quantities for each subsystem. That means, if we allocate the container’s water into five small glasses, the volume of container water is analogous to the sum of the volume of each glass of water. That reveals extensive properties are additive.
Volume is the Additive Extensive Property
Let’s take a ratio of both quantities, i.e., mass/volume. We get another physical quantity called ‘density’ or ‘specific volume‘, which reveals how much matter is within an object’s capacity. When we attempt to estimate the specific volume of water in the spoon and jar, we acquire the exact value of the density of water.
The specific volume value is identical because irrespective of the shape or size of the object, it holds the same amount of matter as per object’s capacity. For the 5ml volume of water into a spoon, the amount of matter stored is 5g, and it calculates the density as 1g/ml. Also, when estimating the mass of water having volume 250ml into a jar, it stores the matter about 250g. So it also has the exact density value of 1g/ml.
Finally, we comprehend that the volume and mass that changes per object capacity is the extensive property. On the other hand, a ratio of extensive properties such as density is an intensive property since it does not depend on the amount of matter stored within either spoon or jar.
Suppose we halved the amount of water into two containers. In that case, the water has the exact density value as the actual value and half the volume and mass values in the individual container. The physical quantities such as mass, volume and density display that extensive property are related to the intensive property.
How Extensive and Intensive Properties are related? (credit: shutterstock)
The change in volume quantity is extensive, depending on the state of the matter.
The volume and mass are only linked in liquids and solids. But in gas, we cannot estimate how much matter the object possesses. But we can compute how much space is occupied by gas. So even if an object’s capacity modifies, the change in volume quantity remains an extensive property within a gas.
Mixed physical properties characterized the gas state, including the volume as extensive property and temperature as the intensive property.
Suppose a gas with a specific temperature is held in a tank. If we put a partition in the center of the tank, the gas gets divided, so does its volume. But the temperature of gas stays exact; even a partition divides the volume of the gas. That reveals even if we estimate how much space the gas occupies, the value of its temperature is independent of its volume.
Is change in Volume an Extensive Property?
As dealing only with intensive properties such as temperature is much more effortless, we can eliminate the mass while conducting any thermodynamic investigation.
The volume of water in each division is one half of the volume of the water in the whole tank. The change in the volume of a gas arises as the amount of matter of gas is distributed. So, the volume quantity is still an extensive property even if it is changed.
If we carry the square root of the volume, its value is neither extensive nor intensive. That’s how even though it is often suitable to express any physical quantities as intensive or extensive, they don’t fall under those classifications.
This article discusses about diffuse reflection examples. Reflection is simply the bouncing back of light whenever it falls on a polished surface.
The reflection can be of many types depending upon the type of object it is falling on and the environmental conditions. This article will discuss about the definition of diffuse reflection first, and then about diffuse reflection examples.
Before knowing about diffuse reflection, let us first get a clear idea on what is the true meaning of reflection.
Reflection is nothing but the bouncing back of light. This happens when it falls on a polished or shiny surface. Due to this phenomenon we can see different types of images in mirrors. The image type depends upon the type of mirror or the reflecting surface.
What is diffuse reflection?
In specular reflection, the incident ray will fall on the reflecting surface and get reflected back in one direction only. Whereas in diffuse reflection the case is not the same.
In diffuse reflection, the incident ray falls on the mirror and gets reflected back into multiple directions. This is something which does not happen in conventional specular reflection. This type of reflection takes place due to the rough nature of the reflecting surface.
How diffuse reflection is formed?
The sole reason for a reflection to be diffused is the surface of the reflecting object. When a rough surface is used for reflection, diffuse reflection takes place.
Diffuse reflection is quite normal because no matter how polished a surface is, irregularities are always there. And where there are irregularities, there is diffuse reflection. Even tiny imperfections can cause diffuse reflection.
Diffuse reflection example
Every thing we see around is a result of diffuse reflection taking place. If we see closely, no object is completely smooth. They all have some irregularities taking place. Now these irregularities are what causes diffuse reflection.
Let us look at some examples of diffuse reflection given below-
Bicycle reflectors
These reflectors are made in such a way that when light falls on them they illuminate spreading red light in multiple directions.
Clothing
Clothes absorb some of the light and reflect some of the light. For example black coloured clothes absorb major part of the light falling on it whereas white clothes will reflect most of the light falling on it.
Paper
A paper acts as transluscent film which allows only a certain portion of light to pass through and reflects remaining light in to multiple directions.
Butter paper
Butter paper also absorbs some portion of the light and reflect remaining part of the light in other directions.
Translucent film
As discussed above, a transluscent fil will reflect some of the light in multiple directions.
Cardboard
A cardboard has a rough surface which results in uneven reflection of light or diffuse reflection.
Rough surface finish on wood
An improper finish on wood will produce uneven reflection.
Car body covered with dust
Dust particles get settled on the car’s surface creating a rough surface. This roughness causes diffuse reflection when light rays fall on the car’s surface.
Metals covered with dust
Dust particles act as irregularities on the surface of the metals. These irregularities will produce diffuse reflection.
Plastic toys having scratches on it
Plastic toys will show specular reflection when their surfaces are polished but will show diffuse reflection when there are scratches on it.
Rough plywood
A rough plywood won’t completely reflect the light as a polished plywood does. The light will be reflected in multiple directions giving out an improper reflection.
Glass having scratches
Scratches act as irregularities and thus give rise to diffuse reflection.
Phone cover with broken glass
A broke glass will make the reflecting surface uneven. Uneven surfaces will give rise to diffuse reflections.
Materials with matte finish
Matte finish is a rough finish which produces hazy images of the objects places near them. This is also an example of diffuse reflection.
Uses of diffuse reflection
Almost everything we see around the world is due to diffuse reflection taking place. The uses of diffuse reflection are given below-
Camera– A camera uses diffuse reflection principle to capture vivid objects.
Absorption spectra/ Spectroscopy- Diffuse spectroscopy is used to find the absorption spectra of powdered samples in those cases where transmission spectroscopy won’t work.
Coloured objects- Colours of objects are determined by the average deflection of the wavelength of light.
Importance for vision– Almost everything we see around us is due to diffuse reflection. Only those things which emit light on their own for example sun and those reflections coming out of polished surfaces are not an example of diffue reflection. The sky is blue in colour due to Rayleigh scattering and is an example of diffuse reflection.
Interreflection– in Computer graphics, to achieve global illumnation, difuse interreflection is used.
Diffuse reflection vs Regular reflection
The table below shows the differences between diffuse reflection and regular reflection-
Diffuse reflection
Regular reflection
The incident ray is scattered in multiple directions.
The incident ray is scattered only in one direction.
Forms a blurry image.
Forms a clear image.
It can happen that no image is formed
It forms an image always.
Happens on rough surfaces.
Happens on smooth surfaces only.
Table: Difference between diffuse reflection and regular reflection
Diffuse reflection vs scattering
The table shown below gives the differences between diffuse reflection vs Scattering. Although both may appear similar but have many differences associated with them.
Diffuse Reflection
Scattering
In diffuse reflection, absorption does not take place.
In scattering, the light waves undergo complete absorption and then the waves are scattered/dispersed.
The wavelength of the light does not get changed.
The wavelength of the light changes after scattering takes place. The best example is the colour of sky when sunlight is scattered by the atmosphere.
The waves bounce up after falling on the reflecting surface.
The waves get absorbed by the surface and then they are dispersed in multiple directions.
Table: Difference between diffuse reflection and scattering
Specular reflection is the conventional reflection which takes place when a ray of light falls on a reflected surface and gets bounced back in a single direction.
This is the case that usually takes place when light falls on a smooth and polished surface. The examples of specular reflection include- reflection from a conventional mirror, water bodies etc.
What causes diffuse reflection?
In the above section, we got an idea about how a diffuse reflection take place Let us dig deeper into its mechanism.
When the light rays fall on a rough surface, the light rays are actually hitting a plane having a lot of irregularitites. Due to these irregularities, the reflected rays also get an irregular direction causing an uneven reflection or diffuse reflection.
This article discusses about classical conditioning examples. Conditioning can be defined as invoking stimulus from someone with the help of neutral stimulus and unconditioned stimulus.
It so happens with our brains that it attaches random things with our favourite things even though they are not related to each other. This happens when those random things were present when the favourite thing was about to take place. This creates a pleasant memory about the random thing. Let us discuss more about this in detail.
An unconditioned stimulus is used in classical conditioning that brings out an automatic response from the subject.
This kind of stimulus is generally related to the subject’s interests. For humans it can be money, food, opposite gender, travel places, hobbies like playing and painting etc. We will discuss more about such stimulus and their related responses in this article.
There can be various kinds of unconditioned stimulus, they depend on the subject’s field of interests. Following are the examples of unconditioned stimulus-
Feather tickling your nose
When a feather tickles your nose, we immediately give a response so as to get rid of the tickling. This is a type of unconditioned stimulus.
Cutting up an onion
When an onion is cut, the chemicals inside the onion make humans cry. This is an immediate response given by humans and hence considered as an unconditioned stimulus.
Animal running to its food
For an animal the food is a type of unconditioned stimulus. This so happens because after looking at the food, the animal gives an immediate response.
Humans getting excited over salary day
A salary day is nothing but the first day of the month. Humans get excited over this date and hence the salary day can be considered as an unconditioned stimulus.
Kids getting excited for PT period’s bell
After hearing the bell for PT period, students get excited so as they know now is their playing time. This specific bell brings out an immediate response in students and hence the bell can be considered as an unconditioned response.
A song that reminds you of some person
When you hear a song, we can sometimes recall someone after hearing the song. This happens as a result of the song being an unconditioned stimulus for you.
Smell from chinese food makes us sneeze
Chinese food is filled with some spices which bring you lots of sneezes. When we go near the chef who is preparing chinese food, we immediately start sneezing. This can be considered as unconditioned stimulus.
Examples of classical conditioning
Now we know the meanings of neutral stimulus, classical conditioning and unconditioned stimulus. We can now look at some examples of classical conditioning to get a clearer idea of what actually it is.
Training a dog with whistle and its favourite food.
Here the whistle acts as an unconditioned stimulus. We can observe that after bringing food with the whistle, the dog starts responding to whistle alone also. This is an example of classical conditioning.
Students getting excited over PT period’s bell
Students don’t get excited over any normal bell unless it is PT period’s bell. If their tone of bell is different then even if the bell is for someone else, the students will immediately get excited.
Training our mind to stay up after hearing alarm bell
After hearing the alarm tone for a long time, then our brain starts responding to it the same way even if we hear the bell in the evening time.
Wearing football jersey whenever you go our to play with kids
If we wear football jersey every time we go to play football with kids, then even after we are going somewhere else, the jersey will remind the kids of football only. This is an example of classical conditioning. Here jersey acts as an unconditioned stimulus.
Carrying office bag to office
Carrying office bag to office becomes a routine. After some while if we take that bag somewhere else, then we will immediately think of office because that bag acts an unconditioned stimulus.
Oiling your hair before sleeping
If we make oiling an habit then after some time the oil will remind us of sleeping even if it is not bed time. Oil acts as the unconditioned stimulus here.
Brushing your teeth before sleeping
Brushing teeth before sleeping also becomes a routine and hence when we brush our teeth at an odd time, it will remind us of sleeping.
Switching on the TV after you come home
If we have a habit of switching on TV every day after coming home, then we will feel weird if one day we decide to not switch on the TV. This is also a response given to the unconditioned stimulus that is TV.
Hearing the sound of laptop when it is switched on
Hearing this sound will often create a memory in our brains. When we hear this sound from other laptops, it will remind us of our laptop.
Celebrities in advertising
Celebrities in advertisements leave a particular image in our minds. When we see those celebrities somewhere else we get reminded of the original ad.
Aromas in restaurants
Aromas in restaurants also act like unconditioned stimulus. A similar aroma will remind us of that restaurant.
Smartphone tones
Smart phone tones are usually common in all phones. These tones will remind us of our own phone when we hear them from somebody else. This is a perfect example of classical conditioning. We will get up thinking it is our phone.
Fear of dogs
Fear of dogs from a childhood experience will create a huge repulsion from dogs even hitting adult age. This is because our brain gets conditioned that way.
Exam anxiety
Exam anxiety triggers our brain to study more out of tension. This is also an example of classical conditioning.
Recess bell
Recess bells are generally different than other bells. They are longer than usual, so when students hear this bell they get immediately excited about the recess time. This is also an example of classical conditioning.
Holiday music
After listening to music on holidays, we will get reminded of that place after we hear that music somewhere else. This is a perfect example of classical conditioning,
What is neutral stimulus?
Neutral stimulus as the name suggests holds no interest value in itself. It is just a conventional way of gaining someone’s attention.
A neutral stimulus includes a whistle, a cry for help from a person you want to avoid etc. The subject does not feel like reacting to such kind of stimulus. For subjects to start reacting to such stimulus, we need to perform conditioning. Let us study about classical conditioning in sections given below.
What is classical conditioning?
Now as we have learnt the definitions of neutral stimulus and unconditioned stimulus, we can define classical conditioning.
It is the way of mixing neutral stimulus with unconditioned stimulus to get a conditioned response from a subject. This is done to train the subject’s mind to give response to neutral stimulus.
Hardness is a fundamental physical property of matter that describes the resistance of a solid material to being scratched, indented, or deformed. It is a crucial characteristic that determines the suitability and performance of materials in various applications, from construction and manufacturing to jewelry and gemology. In this comprehensive guide, we will delve into the intricacies of hardness, its measurement, theoretical explanations, and practical applications.
Measurable Data on Hardness
Hardness Scales
The hardness of materials is typically measured using standardized scales, the most well-known being the Mohs hardness scale. The Mohs scale ranges from 1 (softest) to 10 (hardest), with each number corresponding to a specific mineral. For example, talc has a hardness of 1, while diamond has a hardness of 10.
Another commonly used scale is the Knoop hardness scale, which provides a more quantitative measure of hardness. The Knoop hardness number (KHN) is determined by the depth and area of an indentation made by a diamond-tipped indenter under a controlled load. The KHN values for various materials can range from 40-50 for soft aluminum to 7,000-8,000 for the extremely hard diamond.
Scratch Test
The scratch test is a simple and effective method for determining the relative hardness of materials. It involves using a harder material to scratch the surface of a softer material. If the harder material can leave a visible scratch on the softer material, then the harder material is considered to be of a higher hardness.
Indentation Test
The indentation test is a more quantitative approach to measuring hardness. It involves applying a controlled force to the surface of a material using a sharp object, such as a diamond or steel tip. The resulting indentation is then measured, and the hardness can be calculated using the formula:
$H = \frac{P}{A}$
where $H$ is the hardness, $P$ is the applied force, and $A$ is the area of the indentation.
Quantifiable Data on Hardness
The hardness of materials can be quantified using various scales, providing a more precise and comparable measure of this physical property.
Mohs Hardness Scale
Talc: 1
Copper: 2.5-3
Steel: 5-6
Diamond: 10
Knoop Hardness Scale
Aluminum: 40-50 KHN
Copper: 80-100 KHN
Steel: 150-200 KHN
Diamond: 7,000-8,000 KHN
Theoretical Explanation of Hardness
Hardness is a physical property that arises from the arrangement and bonding of atoms within a material. The strength of these atomic bonds and the crystal structure of the material determine its resistance to deformation or scratching.
For example, diamond has an extremely strong and rigid crystal structure, with each carbon atom covalently bonded to four other carbon atoms. This high degree of bonding and the compact arrangement of the atoms make diamond the hardest known natural material.
In contrast, materials like graphite (found in pencils) have a layered crystal structure with weaker van der Waals forces between the layers, making them relatively soft and easy to scratch.
Theorems and Formulas
The hardness of a material can be calculated using the indentation test and the formula:
$H = \frac{P}{A}$
where $H$ is the hardness, $P$ is the applied force, and $A$ is the area of the indentation.
Examples of Hardness
Graphite vs. Diamond
Graphite, a form of carbon, has a Mohs hardness of 1-2, while diamond, another form of carbon, has a Mohs hardness of 10. This dramatic difference in hardness is due to the distinct crystal structures and bonding arrangements of these two allotropes of carbon.
Metal Hardness
Metals like copper and aluminum are relatively soft, with Mohs hardness values around 2.5-3. In contrast, steel is much harder, with a Mohs hardness of 5-6. This difference in hardness is attributed to the stronger crystal structure and higher bond strength in steel compared to softer metals.
Numerical Problems
A material has a Knoop hardness of 120 KHN. If the applied force is 10 N, what is the area of the indentation?
This article discusses about specular reflection examples. The phenomenon of bouncing back of light when it falls on a polished surface is called as reflection.
Specular reflection is very common and typically means a mirror like reflection. It can be observed in our day to day lives. This article first discusses about what is reflection, types of reflection and then about different examples of specular reflection.
As discussed in above sections, the light bounces back after falling on a polished or shiny surface. This phenomenon is called as reflection.
When we see ourselves in the mirror, it is due to reflection. Only polished surfaces can reflect back the light completely. The light will pass through the glass if it is transparent from both the sides. One side has to be opaque in order for the glass to exhibit reflection. We will discuss about how reflection takes place in below sections of this article.
What is specular reflection?
Specular reflection is a type of reflection which means mirror like reflectance of light when it falls on a shiny body.
Specular obeys the law of reflection. The angle made my incident ray and normal is the same as the angle made by reflected ray and normal. We shall see more about law of reflection and mechanism of reflection in below sections.
In scattered reflection, the rays of reflection are unevenly scattered in all directions unlike specular reflection.
In diffuse reflection, the reflected rays make unequal angles with the vertical. The reflected rays scatter in multiple directions rather than one.
Examples of specular reflection
Specular reflection can be observed every where in our day to day lives. Whenever we go out in public places or even sit inside our classrooms, specular reflection can be observed in some or the other way.
Let us see more about specular reflection by looking at some examples. They are given below-
Conventional plane mirror
A conventional rectangular plane mirror like we see in washrooms and wardrobes follow the principle of specular reflection. The incident rays come from the object standing in front of the mirror, these incident rays are reflected back at the same angle. Here, the angle of incidence is zero hence the reflected ray also makes zero degrees with the normal meaning both incident ray and reflected ray co incide each other. The object’s reflection will be visible.
Concave mirrors
In concave mirrors, we can usually see an inverted image because of the curvature of concave mirrors.
Glasses on the side walls of malls/shops
Glasses on the side walls of malls are cleaned thoroughly, this way the glasses become a polished surface. Hence we can see our own reflection on the glasses when we go near those glasses.
Polished ceramic mug
A ceramic mug also acts like a mirror when it is polished properly. We can see our own reflection when we are holding the mug.
Glare on sunglasses
When we clean the sunglasses, they become polished surfaces. Hence a person standing in front of us can see their reflection from our sunglasses.
Steel utensils
Steel utensils also act like polished surfaces. We will be able to see reflection of the object if it is placed near to the mirror. Metal body phones- Metallic finish acts like a polished surface, any light falling on such a surface is reflected back.
Car body
A car body is usually made of glass fiber on which a polished finish is given. Due to polished finish, we can see our reflections when we stand beside a car. A dirty car won’t be able to reflect our image as it is not polished.
Water body
A water body such as lakes and rivers are usually still and reflects the objects near them. A perfect example of this is reflection of sky in the river and lake. The lake appears to be blue because of reflection of sky.
Polished plastic surface
When a plastic surface is polished, we can see our reflection on it. This is also due to specular reflection.
Ionospheric reflection
Radio waves are reflected in ionosphere. This is an example of specular radiation of waves.
Reflection of radar waves
When the enemy aircraft enters our air base, our radar detects it. This happens because the radar waves are reflected back to the radar after striking on aircraft.
Acoustic mirrors
Even sound can be reflected using acoustic mirrors. This is an example of specular reflection of non electromagnetic waves.
Atomic mirrors
Atoms can be reflected using atomic mirrors. They also follow specular reflection.
Glossy paper
A glossy paper that are used in crafts and decorative purposes also reflect the light. This is also an specular reflection.
Scissors with fine finish
Most scissors are made with metallic alloys and plastics. Both materials when polished give a fine reflection.
Pupil of eye
Pupil of eye also reflects light, when we see other person in the eye then we can observe our reflection in it.
How does specular reflection works?
In above sections, we have discussed what specular reflection is. Now we will discuss how the specular reflection works.
When an incident ray of light strikes a polished surface (also called as specular surface), it gets reflected back with an exact angle at which the incident ray struck on the surface. A person standing in the path of reflected ray will be able to observe the image of the source object from where the incident ray was coming.
How to calculate specular reflection?
Specular reflection can be calculated with the help of Phong Model which was developed by computer graphics researcher Bui Toung.
The specular reflection is a dot product of two vectors. The formula is given below:
Specular reflection= V.R
Where, V is the viewing direction
R can be given by the formula given below-
R=2.(N.L)N-L
Where,
L is the incident light direction
Law of reflection
In optics, there three defined laws of reflection. They are given below-
The angles made by incident ray and reflected ray with the normal are same.
The incident ray, reflected rays and the normal all three exist in same plane.
Both the incident ray and reflected ray are on the different sides of normal.
Does specular reflection obey law of reflection?
Specular reflection obeys the law of reflection. It satisfies all the conditions that laws of reflection require. The incident ray makes an equal angle with the normal as reflected ray makes.
With that, reflected ray will be on one side of the normal and incident ray will be on the other side of normal. Then most importantly, all the three- normal, incident ray and reflected ray lie on the same plane. Hence, we can say that specular reflection obeys all three laws of reflection.
This article discusses about mirror reflection examples. We all are aware of what mirrors are and how we can see our reflections in it.
This article will discuss about different types of mirrors, the type of reflections they produce and then finally discuss the examples of mirror reflections. We need to keep in mind a simple fact throughout that is mirrors reflect all the incident light falling on them.
Mirror is a polished object made of glass which is painted on one side and polished on other. It is used to reflect the light completely such that we can see virtual image of the objects (incase of plane mirrors).
The paint is applied on one side so that it does not allow the light to completely pass through the glass. The light will reflect back with the same angle at which it was incident. Let us discuss more about mirrors in later sections of this article.
Types of mirrors
A conventional mirror is one that is in rectangular shape. We all use that mirror for looking at our reflections. In reality there are two more types of mirrors that are used in Physics. They are- convex mirrors and concave mirrors.
Let us read more about these mirrors in the section below-
Plane mirror/rectangular mirror– A plane mirror is a flat mirror which are usually used in our homes and malls to see our own reflections. The light falls at zero degrees with the normal and hence the reflected ray also makes zero degrees with the normal. This way we can see our reflection in the plane mirrors.
Concave mirror– Concave mirrors as the name suggests makes a cave like mirror surface. They can make both virtual and real iage depending on the distance of the object from the focus. A spoon’s inner surface is an example of concave mirror.
Convex mirror– Convex mirror is a mirror bulged outwards. This mirror is usualy used in rear view mirrors and on the crossings of road. The out side of spoon is an example of convex mirror.
What is mirror reflection of light?
When light falls on an object, the light may be absorbed, reflected or transmitted through the object. These three things may also take place partially, that is light may get partly absorbed, partly reflected and partly transmitted.
When this light reflected completely after falling on the object, it is called as specular or mirror reflection of light. The image of the object can be seen with no loss of resolution as the light gets reflected completely.
We are aware now that mirror is made up of glass which is painted with grey or black colour on one side and polished on other side.
When the light falls on mirror, the light travels through the glass but does not get through the grey paint. This trapped light is reflected back at the same angle at which it was incident. The image of the object is then observed with no loss of resolution as the light gets reflected completely.
Mirror reflection examples
We all know about mirrors and their uses. Let us discuss some of the examples where we can see mirror reflections. The examples are given below-
Wardrobe mirrors
Wardrobe mirror is an example of plane mirror. We can see our reflections of the same size as that of ours.
Mirrors at changing rooms in malls
Mirrors at changing rooms are also an example of plane mirrors. They are also used for obseving our own reflections in the mirror.
Reflection on water bodies
Reflection on water bodies may be considered as a reflection on plane mirror. We can see the water body appearing as blue in colour because of the reflection of blue sky. The colour of the sky is reflected to our eyes hence we observe that the water is blue.
Mirrors at barber shops
Mirror at barber shops are examples of plane mirror. At barber shops, the mirrors are arranged in such a way that we can even see the back of our heads in the mirror.
Concave mirrors used in labs
In Physics lab, we can observe many types of mirrors out of which one is concave. Thir mirror creates an inverted image of the object when it is located near to the mirror and an enlarged virtual image when it is located farther from the mirror.
Rear view mirrors
Rear view mirrors use convex mirrors. They create slightly enlarged ojects, this is why there is a text written on those mirrors “objects may appear closer than they actually are”
Car body
When a car is cleaned and polished properly, we can observe our own reflection on it.
Pupil of eye
The images formed on the pupil of eye are very small but we can observe them. When a person standing infront of us looks closely into our eye, he/she can observe his/her reflection in our eyes.
Steel spoon
As steel spoon when cleaned acts as a concave mirror and created inverted image when we place an object near to it.
Steel bowl
A steel bowl acts as a convex mirror which akes enlarged images of objects kept near to it.
Steel plate
A steel plate acts as a plane mirror which makes virtual images of same size as that of objects that are kept near to the plate.
Metal objects
Metal objects when polished properly reflect away most of the light falling on them.
Polished plastic toys
Plastic toys when cleaned properly also reflect away most of the light. We can see our reflection on plastic toys once we finish cleaning them.
Tinted windows
Tinted windows don’t allow all the light to enter inside the room during day time, reflecting away most of the light. This way we can see our reflections in this windows if we are standing outside of the room.
Ceramic mugs
Ceramic mugs when polished act as convex mirror and hence we can see our own reflections in it.
Ceramic plates
Ceramic plates when polished act as plane mirrors hence we can see our image of exact same size as that of ours.
Optic fibers
Optic fibers use the principle of total internal reflection. The fibers are sized in such a way that the light will keep reflecting itself and travel from one place to another without losing much of its intensity. Many internet providers use this technology to provide high speed internet.
Static equilibrium refers to a state of balance in which an object or a system is at rest and all forces acting on it are balanced. In other words, the net force and net torque acting on the object are both zero. This state of balance ensures that the object remains in a stable position without any external disturbance.
To illustrate this concept, let’s consider a simple example. Imagine a book sitting on a table. In order for the book to be in static equilibrium, the downward force of gravity acting on the book must be balanced by an equal and opposite force exerted by the table. If these forces are not balanced, the book will either fall or move.
Image by SG0039 – Wikimedia Commons, Wikimedia Commons, Licensed under CC0.Image by SMZinovyev – Wikimedia Commons, Wikimedia Commons, Licensed under CC0.Image by SilverStar – Wikimedia Commons, Wikimedia Commons, Licensed under CC BY 2.5.
Static Equilibrium Equation Examples
To find static equilibrium, we can use equations that relate the forces and torques acting on an object. Let’s explore some basic and complex examples of static equilibrium equations.
Basic Examples of Static Equilibrium Equations
Example 1: Consider a beam supported at two ends. To find the equilibrium, we can use the equation ΣF = 0, where ΣF represents the sum of the forces acting on the beam. By setting this equation to zero, we can solve for the unknown forces and determine if the beam is in static equilibrium.
Example 2: Let’s imagine a simple pulley system with two masses connected by a rope. To find the tension in the rope, we can use the equation ΣT = 0, where ΣT represents the sum of the tensions acting on the rope. By setting this equation to zero, we can calculate the tension and determine if the system is in static equilibrium.
Complex Examples of Static Equilibrium Equations
Example 1: Consider a structure with multiple beams and supports. To find the static equilibrium, we need to analyze the forces acting on each beam and support and ensure that their sum is zero. By solving a system of equations, we can determine the unknown forces and verify if the structure is in static equilibrium.
Example 2: Let’s say we have an object on an inclined plane. To find the equilibrium, we need to consider the forces acting on the object, such as gravity, normal force, and friction. By applying the equations that relate these forces, we can determine the conditions for static equilibrium and whether the object will remain at rest.
How to Know Where the Equilibrium Shifts
In some cases, the equilibrium of an object or system can shift due to external influences. It is essential to understand how to identify and analyze these shifts in equilibrium.
Identifying the Shift in Equilibrium
To identify a shift in equilibrium, we need to compare the forces and torques before and after the external influence. If the net force or net torque changes, it indicates a shift in equilibrium.
Factors Influencing the Shift in Equilibrium
Several factors can influence the shift in equilibrium, including changes in external forces, alterations in the object’s shape or position, and variations in the supporting structures. These factors can cause the equilibrium to shift towards a new position or even disrupt the balance altogether.
Impact of Equilibrium Shift on Static Equilibrium
When the equilibrium shifts, the object or system will experience a change in its position or stability. It is crucial to understand the new equilibrium conditions and analyze the effects of the shift on the forces and torques acting on the object. This analysis helps us assess the stability and predict the behavior of the system in its new equilibrium state.
Calculating Force in Static Equilibrium
Force plays a significant role in static equilibrium, and calculating the forces acting on an object is essential to determine its equilibrium.
Understanding the Role of Force in Static Equilibrium
In static equilibrium, all forces acting on an object must balance each other out. This means that the sum of the forces in any direction must be zero. By calculating the forces, we can determine if the object is in equilibrium or if an external force is causing it to move.
Step-by-step Guide to Calculate Force
To calculate the forces in static equilibrium, follow these steps:
Identify all the forces acting on the object.
Resolve each force into its horizontal and vertical components.
Set up equations for the sum of forces in each direction.
Solve the equations to find the unknown forces.
Verify if the forces balance each other out by summing them and checking if the total is zero.
Worked-out Examples on Force Calculation
Let’s work through an example:
Example: Consider a box resting on a table. The weight of the box is 50 Newtons, and there is a horizontal force of 20 Newtons pushing the box to the right. Determine the force exerted by the table to keep the box in static equilibrium.
Solution: – The weight of the box acts downward, so its vertical component is 50 Newtons. – Since the box is not moving vertically, the table must exert an equal and opposite force of 50 Newtons. – The horizontal force of 20 Newtons is countered by an equal and opposite force of 20 Newtons exerted by the table.
By calculating the forces, we can see that the box is in static equilibrium as the sum of forces in both the vertical and horizontal directions is zero.
Calculating Torque for Static Equilibrium
In addition to forces, torque is another crucial element in static equilibrium. Torque measures the tendency of a force to cause rotation and is essential for analyzing objects that can rotate.
Concept of Torque in Static Equilibrium
Torque is the product of the force applied to an object and the perpendicular distance from the axis of rotation to the point of force application. It is represented by the equation:
where (\tau) represents torque, R is the distance, and F is the force.
Method to Calculate Torque
To calculate torque in static equilibrium, follow these steps:
Identify the point of rotation or the axis.
Determine the force acting on the object.
Find the perpendicular distance between the point of force application and the axis of rotation.
Calculate the torque using the equation (\tau = R \times F).
Verify if the net torque acting on the object is zero.
Examples of Torque Calculation in Static Equilibrium
Let’s work through an example:
Example: Consider a see-saw with a fulcrum in the middle. A person weighing 60 kilograms sits 2 meters away from the fulcrum on one side, while a person weighing 70 kilograms sits 1 meter away on the other side. Calculate the torques exerted by each person and determine if the see-saw is in static equilibrium.
Solution: – The torque exerted by the person weighing 60 kilograms is calculated by multiplying the weight by the distance: (\tau_1 = 60 \times 9.8 \times 2) (assuming acceleration due to gravity is 9.8 m/s²). – The torque exerted by the person weighing 70 kilograms is calculated in the same way: (\tau_2 = 70 \times 9.8 \times 1). – To determine if the see-saw is in static equilibrium, we need to compare the torques. If the torques are equal, the see-saw is in equilibrium.
By calculating the torques, we can determine if the see-saw is in static equilibrium and analyze the forces and distances involved.
Finding Mass in Static Equilibrium
mass is another important factor to consider when dealing with static equilibrium. Determining the mass of an object can help us understand its stability and balance.
Importance of Mass in Static Equilibrium
The mass of an object affects its behavior in static equilibrium. Heavier objects require more force to maintain balance, while lighter objects may be easily tipped over. By finding the mass, we can assess the stability of the object and predict its behavior.
Procedure to Determine Mass
To find the mass in static equilibrium, follow these steps:
Identify the forces and torques acting on the object.
Analyze the equilibrium conditions and equations related to mass.
Set up equations that balance the forces and torques.
Solve the equations to find the mass.
Examples on Finding Mass in Static Equilibrium
Let’s work through an example:
Example: Consider a beam supported at one end with a mass of 10 kilograms. The beam is in static equilibrium, but the position of the support needs to be adjusted. Determine the new position of the support that maintains the static equilibrium.
Solution: – To find the new position of the support, we need to analyze the torques acting on the beam. – The torque exerted by the beam’s weight is calculated by multiplying the mass by the acceleration due to gravity and the distance from the support. – By setting the sum of torques to zero, we can find the new position of the support.
By finding the mass and adjusting the position of the support, we can ensure that the beam remains in static equilibrium.
Checking Static Balance
static balance is an essential aspect of static equilibrium and involves assessing the stability and balance of an object. Let’s explore some techniques to check static balance.
What is Static Balance?
Static balance refers to the even distribution of mass and forces in an object, resulting in a stable position without any tendency to tip or rotate. It involves analyzing the distribution of weight and ensuring that the center of mass is aligned with the base of support.
Techniques to Check Static Balance
To check static balance, consider the following techniques:
Visual Inspection: Visually assess the symmetry and alignment of an object to determine if it appears balanced. Look for any irregularities or signs of tipping or leaning.
Plumb Line Test: Hang a plumb line or string from different points on the object and observe if it hangs vertically. A balanced object will have the string aligned with the center of mass.
Pivot Test: Place the object on a pivot point or fulcrum and observe if it remains stable. A balanced object will stay in position without tipping or rotating.
Relation between Static Balance and Static Equilibrium
static balance and static equilibrium are closely related. static equilibrium refers to the balance of forces and torques acting on an object, while static balance specifically focuses on the even distribution of mass and stability. Achieving static balance is essential for achieving static equilibrium.
By checking static balance, we can ensure that an object is ready to enter a state of static equilibrium.
Static Equilibrium of a Lever
A lever is a simple yet powerful tool that operates based on the principles of static equilibrium. Let’s explore the static equilibrium of a lever and how to find it.
Role of a Lever in Static Equilibrium
A lever is a rigid bar that rotates around a fixed point called the fulcrum. It helps us magnify forces and achieve mechanical advantage. In static equilibrium, the forces and torques acting on a lever must balance each other out.
Steps to Find Static Equilibrium of a Lever
To find the static equilibrium of a lever, follow these steps:
Identify the forces and torques acting on the lever.
Determine the locations of the forces and the fulcrum.
Set up equations that balance the forces and torques.
Solve the equations to find the unknowns, such as the forces or distances.
Verify if the forces and torques balance each other out.
By following these steps, we can analyze the equilibrium of a lever and understand its stability and balance.
Examples of Static Equilibrium in a Lever
Let’s work through an example:
Example: Consider a seesaw with two people sitting on either end. The person on the left weighs 50 kilograms and is sitting 2 meters away from the fulcrum, while the person on the right weighs 70 kilograms and is sitting 1 meter away. Determine if the seesaw is in static equilibrium.
Solution: – To find the static equilibrium, we need to calculate the torques exerted by each person. – The torque exerted by each person is calculated by multiplying their weight by the distance from the fulcrum. – By comparing the torques, we can determine if the seesaw is in static equilibrium.
By analyzing the forces and torques in a lever, we can determine if it is in static equilibrium and predict its behavior.
Calculating Tension in Static Equilibrium
Tension is an essential force to consider in static equilibrium, especially in systems involving ropes, cables, or pulleys. Let’s explore the concept of tension and how to calculate it.
Understanding the Concept of Tension in Static Equilibrium
Tension is a pulling force transmitted through a flexible object, such as a rope or cable. In static equilibrium, the tension in a rope must be balanced to maintain the stability and balance of the system.
Steps to Calculate Tension
To calculate tension in static equilibrium, follow these steps:
Identify the forces and objects connected by the rope or cable.
Analyze the equilibrium conditions and equations related to tension.
Set up equations that balance the forces and torques.
Solve the equations to find the tension in the rope or cable.
Examples of Tension Calculation in Static Equilibrium
Let’s work through an example:
Example: Consider a system with two masses connected by a rope. The masses are in static equilibrium, and the angle between the rope and the horizontal is 30 degrees. Calculate the tension in the rope.
Solution: – To calculate the tension, we need to analyze the vertical and horizontal components of the forces involved. – By using trigonometry, we can determine the vertical and horizontal forces acting on each mass. – By setting up equations that balance the forces, we can solve for the tension.
By calculating the tension in the rope, we can ensure that the system remains in static equilibrium and analyze the forces involved.
And there you have it! A comprehensive guide on how to find static equilibrium. By understanding the concept of static equilibrium, analyzing forces, torques, and masses, and performing calculations, we can determine the stability, balance, and behavior of objects and systems. Whether you are studying physics, engineering, or any other field that involves mechanics, mastering static equilibrium is a fundamental skill that will enhance your understanding and problem-solving abilities. So, go ahead and apply these principles to various scenarios, and explore the fascinating world of static equilibrium!
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Dynamic equilibrium and static equilibrium are two distinct states of equilibrium that differ in their characteristics and applications. This comprehensive guide will provide you with a deep understanding of the key differences, quantifiable data, and practical applications of these concepts in the field of physics.
What is Dynamic Equilibrium?
Dynamic equilibrium is a state where the forward and reverse reactions of a chemical reaction occur at the same rate, resulting in no net change in the concentrations of reactants and products. This state is characterized by the following:
Rate of Forward Reaction Equals Rate of Backward Reaction: In a dynamic equilibrium, the rate of the forward reaction is equal to the rate of the backward reaction, leading to a constant concentration of reactants and products.
Concentrations of Reactants and Products Remain the Same: The concentrations of the reactants and products in a dynamic equilibrium system remain constant over time, as the forward and backward reactions occur at the same rate.
Both Forward and Backward Reactions are Ongoing: In a dynamic equilibrium, both the forward and backward reactions are continuously occurring, with the rates of these reactions being equal.
Closed System: Dynamic equilibrium typically occurs in a closed system, where the total number of particles (reactants and products) remains constant.
Examples of Dynamic Equilibrium:
– The Haber process for the production of ammonia (N₂ + 3H₂ ⇌ 2NH₃)
– The dissociation of acetic acid in water (CH₃COOH ⇌ CH₃COO⁻ + H⁺)
– The evaporation and condensation of water in a closed container
What is Static Equilibrium?
Static equilibrium is a state where there is no motion or change in a system. This state is characterized by the following:
No Chemical Reactions Taking Place: In a static equilibrium, there are no chemical reactions occurring, as the forward and backward reactions have ceased.
Concentrations of Reactants and Products Remain the Same: The concentrations of the reactants and products in a static equilibrium system remain constant over time, as there are no ongoing reactions.
Neither the Forward nor the Backward Reaction Occurs: In a static equilibrium, neither the forward nor the backward reaction is taking place.
Open or Closed System: Static equilibrium can occur in both open and closed systems, as long as there is no net change in the system.
Examples of Static Equilibrium:
– The solubility of a solid in a liquid, where the rate of dissolution equals the rate of precipitation, resulting in no net change in the amount of solid in solution.
– A book resting on a table, where the force of gravity is balanced by the normal force exerted by the table.
– A person standing still, where the forces of gravity and the normal force are in equilibrium.
Key Differences between Dynamic Equilibrium and Static Equilibrium
Reaction Rates: In dynamic equilibrium, the forward and backward reactions occur at the same rate, while in static equilibrium, there are no ongoing reactions.
System Type: Dynamic equilibrium occurs in closed systems, while static equilibrium can occur in both open and closed systems.
Motion: Dynamic equilibrium involves constant motion, as the forward and backward reactions are continuously occurring, while static equilibrium involves no motion.
Quantifiable Data
Rate Constants: In dynamic equilibrium, the rate constants for the forward and reverse reactions are equal, while in static equilibrium, the rate constants are not applicable.
Concentration Ratios: In dynamic equilibrium, the ratio of reactant to product concentrations can vary depending on the rate constants, while in static equilibrium, the concentration ratio remains constant.
Physics Applications
Net Force: In physics, equilibrium is achieved when the net force acting on an object is zero. This can occur in both static and dynamic equilibrium.
Acceleration: In dynamic equilibrium, the acceleration of an object is zero, indicating constant motion with no change in velocity.
Theorems and Formulas
Le Chatelier’s Principle: This principle states that when a system in dynamic equilibrium is subjected to a change in one of the conditions (concentration, temperature, or pressure), the system will shift to counteract the change and re-establish a new dynamic equilibrium.
Formula: K = [C]^c / ([A]^a * [B]^b)
Where:
– K is the equilibrium constant
– [A], [B], and [C] are the equilibrium concentrations of the reactants and products
– a, b, and c are the stoichiometric coefficients of the reactants and products
Equilibrium Constant Expression: The equilibrium constant (K) is the ratio of the product concentrations raised to their stoichiometric coefficients to the reactant concentrations raised to their stoichiometric coefficients.
Formula: K = [C]^c / ([A]^a * [B]^b)
Gibbs Free Energy: The Gibbs free energy change (ΔG) is related to the equilibrium constant (K) by the following equation:
Formula: ΔG = -RT ln K
Where:
– ΔG is the Gibbs free energy change
– R is the universal gas constant
– T is the absolute temperature
– K is the equilibrium constant
Examples and Numerical Problems
Haber Process Example:
Reaction: N₂ + 3H₂ ⇌ 2NH₃
At equilibrium, the forward and backward reaction rates are equal: r₁ = r₂
Equilibrium concentrations: [N₂] = 0.2 M, [H₂] = 0.6 M, [NH₃] = 0.4 M
If [Ag⁺] = 1.3 × 10⁻⁵ M, then [Cl⁻] = Ksp / [Ag⁺] = 1.8 × 10⁻¹⁰ / (1.3 × 10⁻⁵) = 1.3 × 10⁻⁵ M
Figures and Diagrams
Figure 1: Comparison of Dynamic Equilibrium and Static Equilibrium
Figure 2: Illustration of Le Chatelier’s Principle
Conclusion
In summary, dynamic equilibrium and static equilibrium are two distinct states of equilibrium that differ in their characteristics and applications. Dynamic equilibrium involves ongoing forward and backward reactions with equal rates, while static equilibrium involves no chemical reactions. Understanding the key differences, quantifiable data, and practical applications of these concepts is crucial for physics students to excel in their studies and research.
Dynamic equilibrium, in simple words, means equilibrium of bodies that are in motion. In this article we will read about the topic “is dynamic equilibrium a diffusion?”
The pre-requisite for understanding this article is to know about the concept of dynamic equilibrium. Although we will discuss about it in brief to make sure we don’t miss out any detail. We shall start this article by discussing about dynamic equilibrium first and then diffusion.
What is dynamic equilibrium?
Dynamic equilibrium in simple words is a equilibrium of bodies in motion. In chemistry, it relates to reactants and products being used up and being formed at the same rate.
Dynamic equilibrium, in Physics, refers to a closed system where all the forces are continuously acting and are in opposite nature such that the sum of all forces is constant or zero always. The system appears to be stagnant or still but in actual the contents are continuously changing.
Diffusion is related to movement of particles from one location to other. It has a particular condition only then the particles will be able to move. Let us see about this condition in the section given below.
The condition should be that the particles will move only from an area of high concentration to an area of low concentration, if the movement has to take place from low concentration to high concentration then external influence is necessary.
What happens when the concentration of both systems are equal?
Diffusion takes place on its own until there is a difference in concentration of quantities. As soon as the concentration of both systems are equal, equilibrium is achieved.
The movement of particles will not stop, instead the particles will start moving from one system to another at equal rates. This state is called as dynamic equilibrium. In simple words, the rates at which forward reaction and backward reaction are taking place are equal.
The particles still as well be moving from one side to other but at equal rates. That is the amount of particles moving out of one location will be equal to the amount of particles moving in the same location.
Is dynamic equilibrium a diffusion?
Now we are well aware of the meanings of diffusion and equilibrium. It is an easy guess from here onward for the question “is dynamic equilibrium a diffusion?”
In dynamic equilibrium we see that the particles are transferred at equal rates from both the systems such that the net quantities remain same. This is a diffusion process in which the quantities move from one location to another at equal rates.
Types of diffusion
There are two types of diffusion commonly known. We shall discuss about these two types in the section given below.
The two most common types of diffusion are-
Simple diffusion– It is a process in which the particles move through the semi permeable membranes without any significant help from transport proteins hence it is termed as simple diffusion.
Facilitated diffusion– As the name suggests, facilitated diffusion is the movement of particles across the boundary of the system or the cell membrane with the help of a carrier molecule which acts as the host. Unlike simple diffusion, here the particles need help of other molecules for transport.
Examples of diffusion
Diffusion is very important in day to day activities. We see diffusion in daily lives and also it takes place inside our bodies as well. Lets see examples of diffusion-
A tea bag immersed in hot water– The color of water will change after some time because of diffusion.
Air freshener– When we spray air freshener in the room, the particles of air freshener will diffuse in the room which is why we can sense the odour.
Dissolution of sugar- When sugar dissolves in water/milk or any liquid, the liquid becomes sweet. This is a result of diffusion of sugar in the liquid.
Osmosis- Plants take minerals from roots by the process of Osmosis. If plants don’t take minerals from roots then there would have been no life possible on Earth.
Incense stick– The scent of incense stick comes after the diffusion of the smoke with the air molecules of the room. This way the pleasant smell of incense stick reaches to us.
Adding water to noodles– The noodles become soft after addition of water because water content inside the noodles increases as diffusion takes place.
Dialysis- Diffusion of solutes through a semi permeable membrane. Dialysis is a very important breakthrough in medical history.
Factors affecting diffusion
There are various factors affecting diffusion. By changing these factors one by one or simultaneously, we can change the rate of diffusion taking place.
The factors affecting diffusion are given below-
Temperature– Increase in temperature leads to increase in movement of particles (higher kinetic energy). Thus, the rate of diffusion will increase with increase in temperature.
Area of interaction– Higher the area of interaction, higher will be the rate of diffusion.
Size of the particle– If the size of particles are small enough so that they can pass through the membrane easily, the rate of diffusion will be more.
From the examples of diffusion given in above sections, we can make out that diffusion is very important. Without diffusion (osmosis), life would not have been possible on Earth.
The most important significance of diffusion is that it helps the substances to move in and out of cells. Which means that through diffusion we can cut out waste from our bodies. Even plants take use of diffusion to collect nutrients and minerals from the roots.
