Question

Rohan rubbed a plastic ruler to his hair and then took the ruler close to bits of paper. The bits of paper got attracted to the ruler. But when Suresh tried the same with a metal ruler, the bits of paper did not stick to the ruler. He was very confused. Can you explain why this happened?

Answer 1

A metal ruler is a conductor, so the charge of whatever kind it acquires on rubbing against hair flows through the ruler to our body. The ruler gets discharged and does not attract the paper bits. However, a plastic ruler, being an insulator, acquires static electricity on rubbing against hair and attracts the paper bits when brought closer to them.