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 nder, the bits of paper did not
stick to the ruler. He was very confused. Can you explain why this happened?
Answers
Answer:
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.
Answer:
You can observe static electricity if you rub a plastic scale through your hair, then if you place the scale near small pieces of paper, the paper pieces gets attracted to the ruler. The ruler now has an excess of electrons and it is negatively charged. The charged ruler induces an opposite charge in the paper. The pieces of paper are neutral. Electrons will move away from the ruler leaving a positive charge on the paper near the ruler, as opposite charges attract, the paper sticks to the comb. A metal scale, unlike a plastic scale, is a conductor. It gets discharged on coming in contact with human body. As it is not charged it cannot attract the paper bits.