Question

The phenomenon of electromagnetic induction is
(A) The process of charging a body.
(B) The process of generating magnetic fields due to current passing through a coil.
(C) Producing induced current in a coil due to relative motion between a magnet and the coil.
(D) The process of rotating a coil of an electric motor.

Answer 1

Here, you are supposed to know what exactly electromagnetic induction is. In order to proceed in this question, you should consider the Faraday’s Law of electromagnetic induction. Consider the terms and quantities which are included in the Faraday’s Law, these are the current, magnetic field, emf and also the magnetic flux.

Complete answer:
As we are supposed to consider the magnetic field, magnets are the first thing that we will think of. Also, consider a conducting loop which is connected to a galvanometer. Initially the current in the loop is zero. Let the magnet be placed on the axis of the loop. It is observed that when the magnet is moved along the axis of the loop, there is deflection which is seen in the galvanometer. If the magnet is moved towards the loop, current flow is obtained.

If the magnet is moved away from the loop, the current flow is obtained in the opposite direction. The current exists as long as the magnet moves, if the magnet stops moving, the current flow is stopped and no current flows. As you can see that when the magnet is moved, current is induced in the loop.

So, whenever there is a relative motion between a magnet and the coil, current is induced. The change in flux in the area bounded by the closed conducting loop induces emf according to the Faraday’s Law of electromagnetic induction.Hence, the phenomenon of electromagnetic induction is producing induced current in a coil due to relative motion between a magnet and the coil.

Hence, option (C) is correct.

Note: Whenever you come across questions containing electromagnetic induction, the first thing that should occur to you is the Faraday’s Law of electromagnetic induction. The emf induced in the loop is given by $\xi = - \dfrac{{d\Phi }}{{dt}}$ where $\Phi$ is known as flux which is defined as ${\mathbf{B}}.{\mathbf{A}}$. ${\mathbf{B}}$ is the magnetic field strength and ${\mathbf{A}}$ is the area of the loop. The SI unit of the magnetic flux is weber.