Two particles $A$ and $B$ having the same mass have charges $+q$ and $+4q$ respectively. When they are allowed to fall from rest through the same electric potential difference,the ratio of their speeds $v_A$ to $v_B$ will be:

Two thin concentric hollow conducting spheres of radii $R_1$ and $R_2$ bear charges $Q_1$ and $Q_2$ respectively. If $R_1 < R_2$,then the potential of a point at a distance $r$ from the centre $(R_1 < r < R_2)$ is

Charges of $+ \frac{10}{3} \times 10^{-9} \, C$ are placed at each of the four corners of a square of side $8 \, cm$. The potential at the intersection of the diagonals is

Charges of $1 \mu C$ are placed at each of the four corners of a square of side $2 \sqrt{2} \text{ m}$. The potential at the point of intersection of the diagonals is . . . . . . .

$A$ solid conducting sphere with charge $Q$ is surrounded by an uncharged concentric conducting spherical shell. Let $V$ be the potential difference between the surface of the solid sphere and the outer surface of the shell. If the shell is now given a charge of $-3Q$,the new potential difference between the two surfaces is .........$V$.

The ratio of electric potentials at the point $E$ to that at the point $F$ is