The electric field in a region surrounding the origin is uniform and along the $x$ - axis. A small circle is drawn with the centre at the origin cutting the axes at points $A, B, C, D$ having co-ordinates $(a, 0), (0, a), (-a, 0), (0, -a)$; respectively as shown in figure then potential in minimum at the point

Calculate potential on the axis of a disc of radius $R$ due to a charge $Q$ uniformly distributed on its surface.

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. then ${V_A}$ and ${V_B}$

An infinite number of charges each numerically equal to q and of the same sign are placed along the $x-$ axis at $x = 1,2,4,8.... \,metres$. Then the electric potential at $x = 0$ due to this set of charges is

$A$ and $C$ are concentric conducting spherical shells of radius $a$ and $c$ respectively. $A$ is surrounded by a concentric dielectric of inner radius $a$, outer radius $b$ and dielectric constant $k$. If sphere $A$ is given a charge $Q$, the potential at the outer surface of the dielectric is.

Three isolated equal charges are placed at the three comers of an equilateral triangle as shown in figure. The statement which is true for net electric potential $V$ and net electric field intensity $E$ at the centre of the triangle is