LENZ LAW OF ELECTROMGNETIC INDUCTION
image courtesy : google
It was discovered by a Russian scientist H.F.Lenz in 1835. He discovered a simple law giving the direction of the induced current produced in the circuit.
The law states that the induced current produced in the circuit always flows in such a direction that opposes the change or cause that produces it.
If the coil has N number of turns φ is the magnetic flux linked with each turn of the coil then the total magnetic flux linked with the coil at any time is Nφ.
e = -d(Nφ)/dt
e = -Ndφ/dt
e = N(φ2-φ1)/t
LENZ’S LAW IS A CONSEQUENCE OF CONSERVATION OF ENERGY.
Experiment to prove Lenz’s law
Requirements
1. Copper coils are wound on a cylindrical cardboard.
2. The two ends of the coil connected to the sensitive galvanometer.
3. The magnet.
OBSERVATION
![Presentation1_thumb[1].png](https://images.ecency.com/p/TZjG7hXReeVoAvXt2X6pMxYAb3q65xMju8wryWxKrsghkMD8un5knnNT7YfguxXy1cVPAEFRZVGCUheU2zfSULSLMfREi9xGYkrJ4kwJVLnXGFAApQXdVz76Yn1k9brb2r3ZKoRdJLCe8N.png?format=match&mode=fit)
image courtesy
1. The magnet is moved towards the coil.
2. Upper face of the coil acquires north polarity.
3. So work has to be done to move the magnet further against the force of repulsion.
4. When we withdraw the magnet away from the coil it acquires south polarity.
5. Now the work is done against force of attraction.
6. When the magnet is moved, the number of magnetic lines of force linking the coil changes, which causes induced current to flow through the coil.
7. The direction of the induced current according to Lenz’s law is always opposite to the motion of magnet.
8. The work done in moving the magnet is converted into electrical energy.
9. This energy is dissipated as heat energy in the coil.
10. If on the contrary, the direction of the current were to help the motion of the magnet, it would start moving faster increasing the change of magnetic flux linking the coil.
11. This results in increase of induced current.
12. Hence kinetic and electrical energy would be produced without any external work.
13. But it is impossible.
14. Therefore induced current always flows in such a direction to oppose that cause.
15. Thus it proved Lenz’s law is the consequence of conservation of energy.
Thanks for Reading