If there are $n$ capacitors in parallel connected to $V \,volt$ source, then the energy stored is equal to

A thin metallic spherical shell contains a charge $Q$ on it. A point charge $+q$ is placed at the centre of the shell and another charge $q'$ is placed outside it as shown in fig. All  the three charges are positive. The force on the charge at the centre is :-

Four point $+ve$ charges of same magnitude $(Q)$ are placed at four corners of a rigid square frame in $xy$ plane as shown in figure. The plane of the frame is perpendicular to $z-$ axis. If a $-ve$ point charges is placed at a distance $z$ away from the above frame $(z << L)$ then

A charge $2\,\mu C$ is taken from infinity to a point in an electric field, without changing its velocity. If work done against forces is $20\,\mu J$ then potential at that point will be.....$V$

Four dipoles having charge $ \pm e$ are placed inside a sphere. The total flux of ${\vec E}$ coming out of the sphere is 

Calculate the work done in taking a charge $-2 \times 10^{-9} \,C$ from $A$ to $B$ via $C$ is ......... (in diagram)