What is magnetic induction ? Explain with the help of a diagram.

When a piece of iron is placed nearby (or brought near) a magnet, it acts as a magnet i.e., it acquires the properties of a magnet temporarily. But as soon as the magnet is removed, the iron piece no longer remains a magnet. This process is called magnetic induction.

Magnetic induction Method :

To make an iron nail a magnet by magnetic induction, we proceed as follows :

(i) Take a long nail. Put it on the arm of a stand passing through a cork as shown in figure (a). Spread some iron pins on the base of the stand. You will find that the pins do not move towards the nail.

(ii) Now bring one pole (say north pole) of a magnet A near the head of the nail as shown in figure (b). You will notice that now some pins begin to cling to the nail. This shows that in the presence of the magnet, the nail has become a magnet. Actually the head of the nail near the north pole N of the magnet A acquires the south (S) polarity and its tip acquires the north (N) polarity.

(iii) Then remove the magnet A as shown in figure (c). You will see that all the pins fall down. This shows that on removing the magnet A, the nail loses its magnetic property. Thus by magnetic induction, the nail or bar becomes a temporary magnet only in the presence of an external magnet.