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

In a regular polygon of $n$ sides, each corner is at a distance $r$ from the centre. Identical charges are placed at $(n - 1)$ corners. At the centre, the intensity is $E$ and the potential is $V$. The ratio $V/E$ has magnitude.

Four point charges $-Q, -q, 2q$ and $2Q$ are placed, one at each comer of the square. The relation between $Q$ and $q$ for which the potential at the centre of the square is zero is

The radius of a charged metal sphere $(R)$ is $10\,cm$ and its potential is $300\,V$. Find the charge density on the surface of the sphere

A thin spherical insulating shell of radius $R$ carries a uniformly distributed charge such that the potential at its surface is $V _0$. A hole with a small area $\alpha 4 \pi R ^2(\alpha<<1)$ is made on the shell without affecting the rest of the shell. Which one of the following statements is correct?

A uniform electric field of $400 \,v/m$ is directed $45^o$ above the $x$ - axis. The potential  difference $V_A - V_B$ is -.....$V$