explain induction method to produce charge.

When the positively charged body is brought near the two cans A and B, the electrons (-ve charges) from both the cans are attracted and get concentrated on B which is near R. The can A which has lost the electrons is left with an equal amount of positive charge. When the cans are separated, the positive and the negative charges remain on A and B respectively. It is important to keep the positively charged rod R, in the immediate vicinity of B while the cans are separated. Otherwise the negative charge (electrons) would flow back to A. When R is taken away, the charge on A and B spread over the surfaces. So, now A has an induced positive charge and Y an equal amount of induced negative charge.

When a charged body is brought near a conductor, the nearer end is induced with an opposite charge and a similar charge is induced on the farther end. This phenomenon is called electrostatic induction.