Question

In which of the following cases does the electromagnetic induction occur?
(This question has multiple correct options)
A.A current is started in a wire held near a loop of wire.
B.The current is stopped in a wire held near a loop of wire.
C.A magnet is moved through the loop of wire.
D.A loop of wire is held near a magnet.

Answer 1

Hint: Electromagnetic induction is usually described as the production of electromotive force across an electrical conductor with changing magnetic field. Electromagnetic Induction was discovered by Michael Faraday. He observed that when a magnet is moved around a coil or a straight wire, EMF or which we call as voltage, is induced around the coil. Hence, the current is also produced.

Complete answer:
When a current carrying conductor is kept in a varying magnetic field, electromagnetic induction occurs. When we switch on the current, the current starts in a wire held near the loop of wire. Due to this change in current, magnetic fields change too. This results in the phenomenon of magnetic induction in the wire,
When we switch off the current, the current stops in the wire held near a loop of wire. This again leads to the phenomenon of magnetic induction in a wire similar to the case when current was switched on.
When a magnet is moved through a loop of wire, the magnetic field lines in the coil changes. This results in the phenomenon of electromagnetic induction in the coil.
Hence, we can say, the electromagnetic induction occurs when a current is started in a wire held near a loop of wire, the current is stopped in a wire held near a loop of wire and when a magnet is moved through the loop of wire.

So, the correct options are A, B and C.

Note:
There are different ways of varying the magnetic field. Few of them are mentioned below.
- Moving a magnet towards or away from the coil or wire will vary the magnetic field.
- Moving the coil into and out of the region of magnetic field will lead to the change in the magnetic field of the coil.
- Rotating the coil relative to the magnet will cause variation in magnetic field.