Induction is a process in which when an uncharged object is placed very close to a charged object, then without touching charged object, it acquire the opposite charge on the nearer face and other polarity charge on the further end.
Experiment :
1. Bring two metal spheres, A and B, supported n insulating stands, in contact as shown in Fig. (a).
2. Bring a positively charged rod near one of the spheres, say A, taking care that it does not touch the sphere. The free electrons in the spheres are attracted towards the rod. This leaves an excess of positive charge on the rear surface of sphere B. Both kinds of charges are bound in the metal spheres and cannot escape. They, therefore, reside on the surfaces, as shown in Fig. (b).
The left surface of sphere A, has an excess of negative charge and the right surface of sphere B, has an excess of positive charge. However, not all of the electrons in the spheres have accumulated on the left surface of A.
The process is called induction of charge and happens almost instantly. The accumulated charges remain on the surface, as shown, till the glass rod is held near the sphere. If the rod is removed, the charges are not acted by any outside force and they redistribute to their original neutral state.
3. Separate the spheres by a small distance while the glass rod is still held near sphere A, as shown in Fig. (c). The two spheres are found to be oppositely charged and attract each other.
Now, separate the spheres quite apart. The charges on them get uniformly distributed over them, as shown in Fig. (e).
