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.)

$A$ hollow metal sphere is charged with a charge of $3.2 \times 10^{-19} \ C$. If the radius of the sphere is $10 \ cm$,then the electric potential at a distance of $4 \ cm$ from its center will be:

$A$ $200 \text{ J}$ of work is done in moving a charge of $5 \text{ C}$ from a point $A$ where the potential is $-20 \text{ V}$ to another point $B$ where the potential is $V \text{ V}$. The value of $V$ at point $B$ is: (in $text{ V}$)

The diagram shows a small bead of mass $m$ carrying charge $q$. The bead can freely move on a smooth fixed ring placed on a smooth horizontal plane. In the same plane,a charge $+Q$ has also been fixed as shown. The potential at point $P$ due to $+Q$ is $V$. The velocity with which the bead should be projected from point $P$ so that it can complete a circle should be greater than:

How much kinetic energy will be gained by an $\alpha$-particle in going from a point at $70\,V$ to another point at $50\,V$?

Two equal positive charges each of value $q$ are placed at points $A$ and $B$, where $AB = 3x$. A third charge $-3q$ is placed at point $C$ at a distance $x$ from $A$ on the line segment $AB$. The potential energy of the system is nearly ($\epsilon_0$ = permittivity of free space).