At the centre of a half ring of radius $R=10 \mathrm{~cm}$ and linear charge density $4 \mathrm{n} \mathrm{C} \mathrm{m}^{-1}$, the potential is $x \pi V$. The value of $x$ is  . . . . . 

Ten electrons are equally spaced and fixed around a circle of radius $R$. Relative to $V = 0$ at infinity, the electrostatic potential $V$ and the electric field $E$ at the centre $C$ are

Consider three concentric metallic spheres $A, B$ and $C$ of radii $a , b, c$, respectively where $a < b < c$. $A$ and $B$ are connected, whereas $C$ is grounded. The potential of the middle sphere $B$ is raised to $V$, then the charge on the sphere $C$ is

There is a uniform electrostatic field in a region. The potential at various points on a small sphere centred at $P$, in the region, is found to vary between in the limits $589.0\,V$ to $589.8\, V$. What is the potential at a point on the sphere whose radius vector makes an angle of $60^o$ with the direction of the field ?........$V$

Two identical metal balls of radius $r$ are at a distance $a (a >> r)$ from each other and are charged, one with potential $V_1$ and other with potential $V_2$. The charges $q_1$ and $q_2$ on these balls in $CGS$ esu are

An electric charge $10^{-8}\  C$  is placed at the point $ (4\,m, 7\,m, 2\,m)$. At the point $(1\,m, 3\,m, 2\,m)$, the electric