Eight drops of mercury of equal radii and possessing equal charge combine to form a big drop. If the capacity of each drop is $C$, then capacity of the big drop is

Three point charges $+q,+2 q$ and $+4 q$ are placed along a straight line such that the charge $+2 q$ lies at equidistant from the other two charges. The ratio of the net electrostatic force on charges $+q$ and $+4 q$ is

A particle of mass 2 g and charge $6 \mu \mathrm{C}$ is accelerated from rest through a potential difference of 60 V . The speed acquired by the particle is

Two spheres $A$ and $B$ of radii 4 cm and 6 cm are given charges of $80 \mu \mathrm{C}$ and $40 \mu \mathrm{C}$ respectively. If they are connected by a fine wire, the amount of charge flowing from one to the other is