Question

What do you understand by electromagnetic induction ?

Hint:

The key phrase for electromagnetic induction is "changing magnetic field". A stationary magnet near a stationary coil will not induce any current. There must be relative motion or a change in the field's strength. This principle is how almost all commercial electricity is generated.

Answer 1

Electromagnetic induction is a fundamental principle of electromagnetism discovered by Michael Faraday in 1831.
\[\begin{array}{rl} \bullet & \text{Definition: It is the phenomenon of producing an induced electromotive force (e.m.f.), and hence an electric current, in a closed electrical circuit by changing the magnetic field (or magnetic flux) linked with the circuit. } \\ \bullet & \text{Methods of Induction: A current can be induced in a coil by:} \\ \bullet & \text{Moving the coil in a stationary magnetic field.} \\ \bullet & \text{Moving a magnet relative to a stationary coil.} \\ \bullet & \text{Changing the magnetic field around a stationary coil (e.g., by changing the current in a nearby coil).} \\ \bullet & \text{Principle: The core idea is that a changing magnetic environment creates an electric field, which drives the current. The magnitude of the induced e.m.f. is proportional to the rate of change of magnetic flux (Faraday's Law of Induction). } \\ \bullet & \text{Applications: This principle is the basis for the operation of electric generators, dynamos, transformers, and induction motors. } \\ \end{array}\]