Write down the faraday law of electromagnetic induction
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In 1831, Michael Faraday, an English physicist gave one of the most basic laws of electromagnetism called Faraday's law of electromagnetic induction. This law explains the working principle of most of the electrical motors, generators, electrical transformers and inductors. This law shows the relationship between electric circuit and magnetic field. Faraday performs an experiment with a magnet and a coil. During his experiment, he found how emf is induced in the coil when flux linked with it changes.
Faraday's Experiment
RELATIONSHIP BETWEEN INDUCED EMF AND FLUX In this experiment, Faraday takes a magnet and a coil and connects a galvanometer across the coil. At starting, the magnet is at rest, so there is no deflection in the galvanometer i.e needle of galvanometer is at the center or zero position. When the magnet is moved towards the coil, the needle of galvanometer deflects in one direction. When the magnet is held stationary at that position, the needle of galvanometer returns back to zero position. Now when the magnet is moved away from the coil, there is some deflection in the needle but in opposite direction and again when the magnet becomes stationary, at that point with respect to coil, the needle of the galvanometer returns back to the zero position. Similarly, if magnet is held stationary and the coil is moved away and towards the magnet, the galvanometer shows deflection in similar manner. It is also seen that, the faster the change in the magnetic field, the greater will be the induced emf or voltage in the coil.
Position of magnet Deflection in galvanometer
Magnet at rest No deflection in galvanometer
Magnet moves towards the coil Deflection in galvanometer in one direction
Magnet is held stationary at same position (near the coil) No deflection in galvanometer
Magnet moves away from the coil Deflection in galvanometer but in opposite direction
Magnet is held stationary at same position (away from the coil) No deflection in galvanometer
Conclusion: From this experiment, Faraday concluded that whenever there is relative motion between conductor and a magnetic field, the flux linkage with a coil changes and this change in flux induces a voltage across a coil.
Michael Faraday formulated two laws on the basis of above experiments. These laws are called Faraday's laws of electromagnetic induction.
Faraday's Laws
Faraday's First Law
Any change in the magnetic field of a coil of wire will cause an emf to be induced in the coil. This emf induced is called induced emf and if the conductor circuit is closed, the current will also circulate through the circuit and this current is called induced current.
Method to change magnetic field:
By moving a magnet towards or away from the coil
By moving the coil into or out of the magnetic field.
By changing the area of a coil placed in the magnetic field
By rotating the coil relative to the magnet.
Faraday's Second Law
It states that the magnitude of emf induced in the coil is equal to the rate of change of flux that linkages with the coil. The flux linkage of the coil is the product of number of turns in the coil and flux associated with the coil.
Faraday Law Formula
Consider, a magnet is approaching towards a coil. Here we consider two instants at time T1 and time T2. Flux linkage with the coil at time, Flux linkage with the coil at time, Change in flux linkage, Let this change in flux linkage be, So, the Change in flux linkage Now the rate of change of flux linkage Take derivative on right hand side we will get
The rate of change of flux linkage But according to Faraday's law of electromagnetic induction, the rate of change of flux linkage is equal to induced emf. Considering Lenz's Law. Where, flux Φ in Wb = B.A
B = magnetic field strength
A = area of the coil
HOW TO INCREASE EMF INDUCED IN A COIL
By increasing the number of turns in the coil i.e N, from the formulae derived above it is easily seen that if number of turns in a coil is increased, the induced emf also gets i
Faraday's Experiment
RELATIONSHIP BETWEEN INDUCED EMF AND FLUX In this experiment, Faraday takes a magnet and a coil and connects a galvanometer across the coil. At starting, the magnet is at rest, so there is no deflection in the galvanometer i.e needle of galvanometer is at the center or zero position. When the magnet is moved towards the coil, the needle of galvanometer deflects in one direction. When the magnet is held stationary at that position, the needle of galvanometer returns back to zero position. Now when the magnet is moved away from the coil, there is some deflection in the needle but in opposite direction and again when the magnet becomes stationary, at that point with respect to coil, the needle of the galvanometer returns back to the zero position. Similarly, if magnet is held stationary and the coil is moved away and towards the magnet, the galvanometer shows deflection in similar manner. It is also seen that, the faster the change in the magnetic field, the greater will be the induced emf or voltage in the coil.
Position of magnet Deflection in galvanometer
Magnet at rest No deflection in galvanometer
Magnet moves towards the coil Deflection in galvanometer in one direction
Magnet is held stationary at same position (near the coil) No deflection in galvanometer
Magnet moves away from the coil Deflection in galvanometer but in opposite direction
Magnet is held stationary at same position (away from the coil) No deflection in galvanometer
Conclusion: From this experiment, Faraday concluded that whenever there is relative motion between conductor and a magnetic field, the flux linkage with a coil changes and this change in flux induces a voltage across a coil.
Michael Faraday formulated two laws on the basis of above experiments. These laws are called Faraday's laws of electromagnetic induction.
Faraday's Laws
Faraday's First Law
Any change in the magnetic field of a coil of wire will cause an emf to be induced in the coil. This emf induced is called induced emf and if the conductor circuit is closed, the current will also circulate through the circuit and this current is called induced current.
Method to change magnetic field:
By moving a magnet towards or away from the coil
By moving the coil into or out of the magnetic field.
By changing the area of a coil placed in the magnetic field
By rotating the coil relative to the magnet.
Faraday's Second Law
It states that the magnitude of emf induced in the coil is equal to the rate of change of flux that linkages with the coil. The flux linkage of the coil is the product of number of turns in the coil and flux associated with the coil.
Faraday Law Formula
Consider, a magnet is approaching towards a coil. Here we consider two instants at time T1 and time T2. Flux linkage with the coil at time, Flux linkage with the coil at time, Change in flux linkage, Let this change in flux linkage be, So, the Change in flux linkage Now the rate of change of flux linkage Take derivative on right hand side we will get
The rate of change of flux linkage But according to Faraday's law of electromagnetic induction, the rate of change of flux linkage is equal to induced emf. Considering Lenz's Law. Where, flux Φ in Wb = B.A
B = magnetic field strength
A = area of the coil
HOW TO INCREASE EMF INDUCED IN A COIL
By increasing the number of turns in the coil i.e N, from the formulae derived above it is easily seen that if number of turns in a coil is increased, the induced emf also gets i
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Answer:Faraday's Law of Electromagnetic Induction :
A change in the magnetic environment of the coil or conductor will cause a voltage(emf) induce in the coil. Faraday law is the fundamental relationship which comes from the Maxwell’s equation.
◇ Faraday's First Law : A conductor is induced with an electromotive force when the surrounding magnetic field changes.
◇ Faraday's 2nd Law : The rate of change of field is directly proportional to the magnitude of the electromotive force.
◇ Faraday's 3rd Law : The sense of the induced electromotive force depends on the direction of the rate of the change of the field.
E= – ndǿ/ dt.
In this the induced emf (e) and the change in magnetic flux (d) have opposite signs.
Explanation:
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