(a) A comb run through one’s dry hair attracts small bits of paper. Why? What happens if the hair is wet or if it is a rainy day? (Remember, a paper does not conduct electricity.)
(b) Ordinary rubber is an insulator. But special rubber tyres of aircraft are made slightly conducting. Why is this necessary?
(c) Vehicles carrying inflammable materials usually have metallic ropes touching the ground during motion. Why?
(d) A bird perches on a bare high power line, and nothing happens to the bird. A man standing on the ground touches the same line and gets a fatal shock. Why?

Explanation

This is because when a comb run through one.s dry hair it gets charged by friction.
When the comb is brought near paper without contact it, the molecules in the paper gets polarised. Unlike charges comes towa.rds comb and like charges comes far away from comb. So, the force of attraction is larger than force of repulsion and hence resulting the net force of attraction. Hence, comb attracts small bits of papers. lf the hair is wet or if it is rainy day, friction between hair and the comb reduces. The comb does not get charged and thus it will not attract small bits of paper.