A small sphere of radius $r_{1}$ and charge $q_{1}$ is enclosed by a spherical shell of radius $r_{2}$ and charge $q_{2} .$ Show that if $q_{1}$ is positive, charge will necessarily flow from the sphere to the shell (when the two are connected by a wire) no matter what the charge $q_{2}$ on the shell is.
According to Gauss's law, the electric field between a sphere and a shell is determined by the charge $q_{1}$ on small sphere. Hence, the potential difference, $V$, between the sphere and the shell is independent of charge $q_{2}$. For positive charge $q_{1}$, potential difference $V$ is always positive.
$(a)$ 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?
A body has $-\, 80$ $micro\, coulomb$ of charge. Number of additional electrons in it will be
Sure check for presence of electric charge is
Discuss the method of charging of two spheres by without contact method.
Why can we say that charge of any body is always an integral multiple of $'e'$ ?