describe faraday's magnet and coil experiment which shows the relation between magnetic flux and emf

Dear Student,
According to Faraday's Law, whenever magnetic flux linked with the circuit changes, an emf is induced in it and the magnitude of emf is directly proportional to the change in magnetic flux.
• Experiment:
Considering two different coils of copper wire having large number of turns (say 100 and 500 turns respectively) are taken. They are now inserted over a non-conducting cylindrical roll.
The coil-1, having larger number of turns, is connected in series with a battery and a plug key. Also, the other coil-2 is connected with a galvanometer as shown. The key is initiated and the galvanometer is observed.
We will observe that the needle of the galvanometer instantly jumps to one side and then quickly returns to zero, indicating a momentary current in coil-2. The coil-1 is now disconnected from the battery. Now we will observe that the needle momentarily moves, but to the opposite side. It means that now the current flows in the opposite direction in coil-2.



• Observations:
From these observations, we conclude that a potential difference is induced in the coil-2 whenever the electric current through the coil 1 is changing (starting or stopping). As the current in the first coil changes, the magnetic field associated with it also changes.
Thus the magnetic field lines around the secondary coil also change. Hence the change in magnetic field lines associated with the secondary coil is the cause of induced electric current in it. This is same observation as stated in Faraday's Law.

Regards

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