If a charged spherical conductor of radius $10 \,cm$ has potential $V$ at a point distant $5 \,cm$ from its centre, then the potential at a point distant $15 \,cm$ from the centre will be

$A$ conducting sphere of radius $R$ is given a charge $Q$. The electric potential and the electric field at the centre of the sphere respectively are

$A$ charge of $10\, e.s.u.$ is placed at a distance of $2\, cm$ from a charge of $40\, e.s.u.$ and $4\, cm$ from another charge of $20\, e.s.u.$ The potential energy of the charge $10\, e.s.u.$ is (in $ergs$)

Two point charges $q_1$ and $q_2$ are separated by a distance $d$. What is the increase in potential energy of the system when $q_2$ is moved towards $q_1$ by a distance $x$? $(x < d)$ (where $\frac{1}{4 \pi \varepsilon_0} = K$ is a constant).

Can the potential function have a maximum or minimum in free space? Explain.

If the electric potential of the inner sphere is $10\, V$ and that of the outer shell is $50\, V$,then the potential at the common centre is :- (in $, V$)