The charge on an electron was discovered by

One can define an alpha-volt $(\alpha-V)$ to be the energy acquired by an $\alpha$-particle when it is accelerated by a potential of $1 \,V$. For this problem,you may take a proton to be $2000$ times heavier than an electron. Then,

Four metal conductors having different shapes:
$1.$ $A$ sphere
$2.$ Cylindrical
$3.$ Pear
$4.$ Lightning conductor
are mounted on insulating stands and charged. The one which is best suited to retain the charges for a longer time is:

What is a point charge?

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