In this article, we are going to discuss some magnetic force examples and understand its application in more detail.
Following is a list of some examples and applications of a magnetic force that we are often using and are basically working on the application of a magnetic force:
Examples of the Magnetic Force and Some Application
Magnetic force can be converted to another form such as mechanical to mechanical in attraction and repulsion; mechanical to electrical in generators, microphones; electrical to mechanical in motors, loudspeakers; mechanical to heat energy as eddy current, hysteresis torque devices, etc. and hence magnetic force has wide application in industries, factories, electronic devices, laboratories, etc. Let us discuss some examples of the magnetic force.
Two Bar Magnets
The bar magnet has two poles, one pole of the magnet carries more number of protons having a positive charge, thus making it positive, and another pole constitutes more number of electrons, hence negatively charged.
The positive pole of the magnet will tend to attract towards the negative pole of another magnet as the positive pole with more number of protons will tend to attract electrons from another pole of the magnet towards it and vice versa, thus both showing the forces of attraction towards each other.
Similarly, when two positive or negative poles are bought closer to one another, will show repulsion as the pole already having a majority of the protons will not accept more protons towards it, or a pole with the majority of the electrons will not pull more electrons towards it, hence the force of repulsion is seen by both the poles of the magnet.
This follows Newton’s Third Law, according to which “Every action has an equal and opposite reaction.”The magnitude of the force experienced by each of the poles during attraction or repulsion is always equal, and the force always acts in the opposite direction.
If the positive pole of the magnet is brought closer to the neutral object, then the electrons from the object will get attracted towards the positive charges thus gathering at one side of the object and repels the protons away from it leaving behind the protons on the other side. And thus, the protons and the electrons will get separated from the neutral object forming two different poles of the charged particles.
Current carrying wire
The above diagram represents the conductor of length “L” carrying a current “I” placed in the magnetic field. On application of current, the charges in the conductor will show some mobility and an effect so produced due to the presence of magnetic field is called electromagnetism. The force experienced on the unit length of the wire is given as
F=I(L*B)
If is an angle between the current-carrying wire and the direction of a magnetic field, then the magnitude of the force is
F=ILB\sinθ
This equation shows the relationship between current and a magnetic field.
Two parallel current-carrying wires
Consider two current-carrying wires placed parallel. The magnetic field produced by a current-carrying wire 1 at a distance r from it is given by
B=μ0I1/2πr
The force experienced due to the presence of the second current-carrying wire in parallel with the first carrying current I2 is
F=I2LB1
F=μ0I1I2L/2πr
The force per unit length
F/L=F=μ0I1I2/2πr
The two wires will show some force of attraction when the current flowing in both the wires is in the same direction, likewise, both will repel away if the direction of current is in the opposite direction.
Some applications of the magnetic field
Compass
A compass is a device used to find the direction. It consists of a magnetic needle mounted on a small pin that always points towards the North Pole of the Earth. Since the Earth’s magnetic field is positioned in the North-South direction, the magnetic needle gets align itself in collaboration with the magnetic effect felt due to Earth’s magnetic field.
MRI Scanners
Magnetic Resonance Imaging machines are widely used in medical diagnoses. They produce large magnetic field strength and are used to take pictures of the human organs for detailed studies by passing the radio waves.
Electric Motors
A coil in a motor generates a magnetic field on the application of current. The magnetic field thus produces induces magnetic force with the magnet that causes motion or spinning of the motor. So basically, the magnetic force is utilized by the motor to create mechanical energy from electrical energy.
Speakers
Speaker, microphones are devices that come with an electromagnet that converts the electric signal into audible sound. The electromagnet is like a coil, when current flows through this coil it produces a magnetic field. This coil frequently attracts and repels from the magnet to produce an audio effect.
Refrigerators
Refrigerators have a magnet embedded in their door made up of weak ferromagnetic ceramics like barium ferrite or strontium ferrite. Due to this, the refrigerator door always apt to close itself whenever the refrigerator is opened.
Microwave
Ovens have a magnetron which is a vacuum tube designed to generate or amplify the microwaves by controlling the flow of an electron by applying an external magnetic field. A magnet is placed around this vacuum tube that provides magnetic force and causes the electrons to move in a loop. Thus generating heat and cooking food.
Cars
The car uses electromagnetic property inside the engine for its motion. A magnetic coil is attached to an axle. By turning this magnetic coil, the wheels are also made to turn, thus controlling the steering of the car.
Fans
The magnets in the rotor of a fan are repelled by the stators which increase the movement of the rotor. The electric current switches one of the sets of the magnet and hence, the rotor and stator repel themselves away from each other every cycle of the rotor. This is achieved by the application of the magnetic force.
Magnetic Force
Magnetic force is one among the four fundamental forces. The magnetic force acts perpendicular to the motion of the particles, thus opposing the motion of the charges; hence the charged particles tend to deflect due to the magnetic force.
The magnetic force depends upon the charge and the velocity of the particle in a magnetic field and the external field applied to the conductor and is given by F=qvB. In presence of the external field, the electrons and protons align themselves according to the field applied. The magnetic field density depends upon the density of a magnetic flux crossing per unit cross-sectional area of the material.
Types of magnetic force
1) Attractive Force: When two poles of unlike charges are bought near, both the poles tend to attract towards each other. The force exerted by the poles on each other is known as an attractive force.
2) Repulsive Force: When the two poles of like charges are bought near, the poles repel away from each other. The force felt on each of the poles is known as a repulsive force.
Theory and the Classification of Magnetic Materials
According to the Pauli Exclusion Principle, “No two electrons will have the same quantum number. No more than two electrons can occupy the same orbital. Electrons present in the same orbital must have opposite or anti-parallel spin.”
The electrons pair up with the electrons having an opposite spin and canceling out the magnetic moment produced by each other. Well, the unpaired electron shows the spin and orbital movement of the atom and gives the direction of the magnetic field.
Based on the number of free electrons available, various materials show different magnetic characteristics. If the number of available unpaired electrons is greater, then, the magnetic effects seen in the material will also escalate. The materials are classified as follows:-
Diamagnetic: Diamagnetic materials show the force of repulsion on both the poles of a magnet. These materials tend to oppose the magnetic flux through them and hence are repelled by the magnetic force. Examples: Carbon, Gold, Silver, water, etc.
Paramagnetic: Paramagnetic materials show properties of magnetization only when a strong magnetic force is applied to them. They are weakly attracted to either of the poles of a magnet. Examples: Oxygen, Aluminum, brass, etc.
Ferromagnetic: Ferromagnetic materials are highly magnetized materials. They have many unpaired electrons which are aligned forming colonies of charges and hence becoming highly attractive. They can retain their magnetization and even become a magnet. Examples: Iron, Nickel, Cobalt, etc.
On what factors does the magnetic force depend
The magnetic force basically depends upon the magnitude of the charge, the velocity of a charged particle, and the external magnetic force. In the electromagnetic region, this force is described as Lorentz force and is represented as:
F=q(E+v*B)
Force due to the magnetic field is given as
F=qvB
The magnitude of the magnetic force
F=qvB sin θ
Where θ varies from 0 to 1800 and <1800.
The direction of the force is found out using Fleming’s Right-Hand Rule and Right-Hand Grip Rule as shown below,
Right Hand Grip Rule
The right hand is imagined as the current carrying conductor. The direction of the current is symbolized by the thumb and the field lines are running around the conductor forming concentric circles as seen in the figure.
Fleming’s Right-Hand Rule
In Fleming’s Right-Hand Rule, the thumb shows the direction of force, while the index and middle finger indicate the direction of magnetic field and electric current respectively.
For a current carrying conductor placed in a magnetic field, the force experienced on a unit cross-section length of the wire is given as
F=qvB sin θ
because, velocity = distance/time
Hence, we can rewrite the above equation as:
F=a/LTBsin θ
Current is defined as a charge per unit time and given by I=q/t
Therefore, F=BILsin θ
Read more on “What Objects Have Magnetic Force: Exhaustive Facts On Various Objects“.
Frequently Asked Questions
What force is a magnetic force?
The magnetic force depends upon the majority of the charge carriers, the direction of a field and the current.
The magnetic force is basically the force of attraction and repulsion between the positive and the negatively charged particles.
Consider a wire placed between the two poles of the magnet. If the current flowing in a wire is 15A, find the magnitude and the direction of the force experienced on 10 mm length of the same wire if the magnetic field is 0.2T.
A magnetic field is perpendicular to the direction of the current flowing in the wire, therefore
sin θ=1
The force experienced on a 10mm section of the wire is
F=BIL=0.2T*15A*0.01m=0.01N
If the magnetic field lines are running towards North and the acceleration of the electrons is perpendicular to the direction of the field, then the force is exerted outward.
What material is used to make a horseshoe magnet?
A horseshoe magnet is a U-shaped magnet and both the poles are in the same direction that helps to create a strong magnetic field.
It is made up of AlNiCo an alloy of Iron and an iron bar is attached to the two poles of the magnet to prevent demagnetization. This was previously used in microwave ovens in the magnetron tube.
Also Read:
- What objects have magnetic force
- How to find tangential force
- Newtons law of gravitational force
- Is magnetic field and magnetic force same
- Internal forces examples
- Magnetic field and force
- How to find tension force with friction
- Gravitational force 2
- How organisms adapt to varying accelerative forces
- Atomic force microscopy
Hi, I’m Akshita Mapari. I have done M.Sc. in Physics. I have worked on projects like Numerical modeling of winds and waves during cyclone, Physics of toys and mechanized thrill machines in amusement park based on Classical Mechanics. I have pursued a course on Arduino and have accomplished some mini projects on Arduino UNO. I always like to explore new zones in the field of science. I personally believe that learning is more enthusiastic when learnt with creativity. Apart from this, I like to read, travel, strumming on guitar, identifying rocks and strata, photography and playing chess.
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