$A$ particle $A$ has charge $+q$ and particle $B$ has charge $+4q$,with each of them having the same mass $m$. When allowed to fall from rest through the same electric potential difference $V$,the ratio of their speeds $\frac{v_A}{v_B}$ will be:

The electrostatic potential $V$ at a point on the circumference of a thin non-conducting disk of radius $r$ and uniform charge density $\sigma$ is given by the equation $V = 4 \sigma r$. Which of the following expressions correctly represents the electrostatic energy stored in the electric field of a similarly charged disk of radius $R$?

Prove that electrostatic forces are conservative in nature and define electrostatic potential energy.

Charge $1.6 \times 10^{-7} \text{ C}$ is distributed uniformly over the surface of a spherical conductor of radius $R$. The ratio of the electric potential inside the spherical conductor to the electric field on the surface is . . . . . . .

$A$ hollow metal sphere of radius $15 \,cm$ is charged such that the potential on its surface is $20 \,V$. Then, the potential at the centre of the sphere is (in $V$)

If a $10 \mu C$ charge exists at the centre of a square,the work done in moving a $2 \mu C$ point charge from corner $A$ to corner $B$ of a square $ABCD$ is