Question

When a glass rod is rubbed with a piece of silk cloth charges appear on both?

Answer 1

Due to the attraction. .. .

Answer 2

Rubbing produces charges of equal magnitude but of opposite nature on the two bodies because charges are created in pairs.  When a glass rod is rubbed with silk, electrons from the glass rod are transferred to the silk cloth. The glass rod acquires a positive charge and the silk cloth acquires an equal amount of  negative charge.This phenomenon of charging is called charging by friction. The net charge on the system of two rubbed bodies is zero before and after rubbing.  Therefore in an isolated system, the total charge always remains constant. This is consistent with the law of conservation of energy.