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 doesn't 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?