why is rubbing responsible for transfer of electrons
When two objects are rubbed together, especially if the objects are insulators and surrounding air is dry, the objects acquire equal and opposite charges and an attractive force develops between them. The object that loses electrons becomes positively charged, and the other that gains electrons becomes negatively charged. The force is simply the attraction between charges of opposite sign.
>When a piece of amber, plastic, polythene, or hard rubber is rubbed with fur, electrons are transferred from fur to the other material. Fur acquires net positive charge, since it has fewer electrons than protons. Similarly, the amber, plastic, or hard rubber acquires a net negative charge since they have excess electrons.
>Combing hair charges the comb in the same way.
>Rubbing glass with silk causes the glass to acquire a net positive charge.