Two objects are rubbed against each other. The nature of the electric force between them when they are placed at some distance is:

$(a)$ $A$ 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?

In general,metallic ropes are suspended from the carriers that transport inflammable materials. The reason is:

If a body is charged by rubbing it,its weight:

What is called the polarity of electric charge?

If $10^{9}$ electrons move out of a body to another body every second,how much time is required to get a total charge of $1 \, C$ on the other body?