Question

Two circular coils A and B are placed close to each other. If the current in the coil B is changed, some current will be induced in the coil B. Give reason.

Answer 1

Hint
When two current-carrying conductors are kept close to each other, the change in current in one conductor will induce a current in the other conductor. The relation between the magnetic field and the electric field is given by Michael Faraday. Electric motors and generators work based on this principle.

Complete step by step answer
The production of an electromotive force in a current-carrying conductor due to a varying magnetic field is called electromagnetic induction. The reverse of this process is also possible. We know that moving charges will give rise to a magnetic field.
Here two circular coils A and B are placed close to each other. When the current flowing through the coil A changes, there will be a magnetic field associated with that change in current. Since the coil B is placed closer to the coil A the changing magnetic field will induce a current in the coil B. This is due to the phenomenon of electromagnetic induction.

Note
Electrical generators are devices that make use of this phenomenon. The relative motion of the coil and the magnetic field will give rise to an induced EMF. This is the same principle behind the electric transformer also. In an electric transformer, the current flowing through a coil will give rise to an electric current in the second coil associated with the first coil. When an electric conductor is placed in a stable magnetic field or a stationary conductor is placed in a varying magnetic field there will be a formation of circular currents within the conductor induced due to induction and these currents are called eddy currents.