Two conducting spheres of radii $r_1$ and $r_2$ are equally charged. The ratio of their potentials is (potential of $r_1$ to potential of $r_2$):

$A$ spherical shell of radius $R$ carries a charge $Q$. What is the potential at point $B$ on the surface,at the center $A$,and at point $C$ at a distance $R/2$ from the center?

$A$ hemispherical bowl of radius $R$ is uniformly charged with surface charge density $\sigma$. Find the electric potential at point $A$,which lies on the base at a distance $R/2$ from the center $O$ of the base.

The work done to assemble the three charges in a configuration as shown in the figure is

$A$ hollow metal sphere of radius $5\, cm$ is charged such that the potential on its surface is $10\, V$. The potential at the centre of the sphere is

Two charges $5 \times 10^{-8} \; C$ and $-3 \times 10^{-8} \; C$ are located $16 \; cm$ apart. At what point$(s)$ on the line joining the two charges is the electric potential zero? Take the potential at infinity to be zero.