In the figure shown the electric potential energy of the system is: ( $q$ is at the centre of the conducting neutral spherical shell of inner radius $a$ and outer radius $b$ )
$0$
$\frac{{{\text{k}}{{\text{q}}^2}}}{{{\text{2b}}}}$
$\frac{{{\text{k}}{{\text{q}}^2}}}{{{\text{2b}}}} - \frac{{{\text{k}}{{\text{q}}^2}}}{{{\text{2a}}}}$
$\frac{{{\text{k}}{{\text{q}}^2}}}{{{\text{2a}}}} - \frac{{{\text{k}}{{\text{q}}^2}}}{{{\text{2b}}}}$
Three charges $-q, Q$ and $-q$ are placed respectively at equal distances on a straight line. If the potential energy of the system of three charges is zero, then what is the ratio of $Q: q$ ?
Work done in moving a positive charge on an equipotential surface is
Electric field at a place is $\overrightarrow {E\,} = {E_0}\hat i\,V/m$ . A particle of charge $+q_0$ moves from point $A$ to $B$ along a circular path find work done in this motion by electric field
Consider a spherical shell of radius $R$ with a total charge $+ Q$ uniformly spread on its surface (centre of the shell lies at the origin $x=0$ ). Two point charges $+q$ and $-q$ are brought, one after the other from far away and placed at $x=-a / 2$ and $x=+a / 2( < R)$, respectively. Magnitude of the work done in this process is
There is a uniform spherically symmetric surface charge density at a distance $R_0$ from the origin. The charge distribution is initially at rest and starts expanding because of mutual repulsion. The figure that represents best the speed $V(R(t))$ of the distribution as a function of its instantaneous radius $R(t)$ is