How can you charge a metal sphere positively without touching it?

How does electroscope work ?

$(a)$ 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?

Mention the $SI$ unit and value of fundamental charge. Write its smaller units.

Write definition of unit Coulomb.