If $20 \ J$ of work has to be done to move an electric charge of $4 \ C$ from a point where potential is $10 \ V$ to another point,where potential is $V \ V$,find the value of $V$. (in $V$)

In the following diagram, the work done in moving a point charge from point $P$ to points $A, B$ and $C$ is $W_A, W_B$ and $W_C$ respectively. If there is no charge nearby, then:

Three equal charges are placed at the corners of an equilateral triangle. Which of the graphs below correctly depicts the equally-spaced equipotential surfaces in the plane of the triangle? (All graphs have the same scale.)

Two electric charges of $9 \mu C$ and $-3 \mu C$ are placed $0.16 \ m$ apart in air. There will be a point $P$ on the line joining the two charges and between them where the electric potential is zero. The distance of $P$ from the $9 \mu C$ charge is: (in $m$)

The electrostatic potential energy of the given system of charges placed at the corners of a square of side $a$ is:

Two charged spheres of radii $10\, cm$ and $15\, cm$ are connected by a thin wire. No current will flow,if they have