Question

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

Answer 1

Changing current in a coil leads to a change in magnetic flux (It produces a time-varying magnetic field) around it. According to Faraday’s law time-varying, the magnetic flux through a conductor induces potential difference and thus current in the conductor

Complete Step-by-step solution
As we know from the question coils A and B are placed close to each other and the current in coil A is changed this produces a time-varying magnetic field, as both coils are placed together this leads to a change in magnetic flux through coil B and from Faraday’s law which states that “Time-varying magnetic field through a conductive loop induces current in that loop.'' This produces EMF in it which in turn produces current in coil B.

Additional information
1. The above explanation can also be represented through the mathematical equation of Faraday’s law the equation is$E = \left| {\dfrac{{d\phi }}{{dt}}} \right|$ E is E.M.F. induced, $\left| {\dfrac{{d\phi }}{{dt}}} \right|$ is the magnitude of instantaneous change of flux with respect to time. Here due to coil A $\phi$ (magnetic flux) is changing with time across coil B which produces E (E.M.F.) which leads to flow of current.
2. Further, a law came which was called Lenz Law which gave the direction of electric current induced in the conductor through which magnetic flux is changing with time.

Note: If in the question it is not mentioned that both coils are placed close to each other then we can’t say the same thing as in that case it is possible that the coils are placed far from each other and with distance change in magnetic flux would not be so significant.