Charges $+q$ and $-q$ are placed at points $A$ and $B$ respectively which are at distance $2\,L$ apart, $C$ is the midpoint between $A$ and $B$ . The work done in moving a charge $+ Q$ along the semicircle $CRD$ is
$ - \frac{{qQ}}{{6\pi \,{ \in _0}L}}$
$\frac{{qQ}}{{4\pi \,{ \in _0}L}}$
$\frac{{qQ}}{{2\pi \,{ \in _0}L}}$
$\frac{{qQ}}{{6\pi \,{ \in _0}L}}$
Two point charges placed at a distance $r$ in air experience a certain force. Then the distance at which they will experience the same force in a medium of dielectric constant $K$ is
Two condensers $C_1$ and $C_2$ in a circuit are joined as shown in figure. The potential of point $A$ is $V_1$ and that of $B$ is $V_2$. The potential of point $D$ will be
The conducting spherical shells shown in the figure are connected by a conductor. The capacitance of the system is
Four charges are placed at the circumference of a dial clock as shown in figure. If the clock has only hour hand, then the resultant force on a charge $q_0$ placed at the centre, points in the direction which shows the time as
The value of electric potential at any point due to any electric dipole is