$A$ regular hexagon of side $9 \ cm$ has a charge $5 \mu C$ at each of its vertices. The electric potential at its centre is $..........V$. $(k = 9 \times 10^9 \ Nm^2 C^{-2})$

The potential at a point,due to a positive charge of $100\,\mu C$ at a distance of $9\,m$,is

Three charged particles having charges $q, -2q$,and $q$ are placed in a line at points $(-a, 0), (0, 0)$,and $(a, 0)$ respectively. The expression for electric potential at $P(r, 0)$ for $r \gg a$ is ...............

Three concentric metallic shells $A, B$ and $C$ of radii $a, b$ and $c$ $(a < b < c)$ have surface charge densities $\sigma, -\sigma$ and $\sigma$ respectively. Find the potentials ${V_A}$ and ${V_B}$.

$A$ point charge $q$ is held at the centre of a circle of radius $r$. $B$ and $C$ are two points on the circumference of the circle,and $A$ is a point outside the circle. If $W_{AB}$ represents the work done by the electric field in taking a charge $q_0$ from $A$ to $B$,and $W_{AC}$ represents the work done from $A$ to $C$,then:

$A$ spherical drop of liquid carrying charge $Q$ has potential $V_0$ at its surface. If two drops of same charge and radius combine to form a single spherical drop,then the potential at the surface of the new drop is (Assume $V=0$ at infinity.)