Question

When a glass rod is rubbed with silk the free electrons of glass rod are transferred to silk. But glass is a insulator and insulators do not have free electrons. So how did free electrons from glass rod get transferred to silk if glass rod doesn’t even have free electrons

Answer 1

The concept you are thinking to apply here is wrong. Here is the correct explanation.

Glass happens to lose electrons easily, and silk grabs them away from the glass atoms, so after rubbing the glass becomes positively charged and the silk becomes negatively charged.


When silk is rubbed on a glass rod, an electrostatic charge is generated in a phenomenon known as the triboelectric effect. It is this electric charge that gives you a shock in winter when your rubber-soled shoes rub against a carpeted floor. The triboelectric series is a list of materials sorted according to their electrostatic behavior; using the list, you can predict the electrostatic effects when silk is rubbed on a glass rod.