Sixty four conducting drops each of radius $0.02 m$ and each carrying a charge of $5 \,\mu C$ are combined to form a bigger drop. The ratio of surface density of bigger drop to the smaller drop will be ............
$1: 4$
$4: 1$
$1: 8$
$8: 1$
If electric potential of the inner sphere is $10\, volt$ and that of the outer shell is $50\, volt$ then potential at common centre is :-......$V$
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 central charge due to the shell is :-
A hollow conducting sphere is placed in an electric field produced by a point charge placed at $P$ as shown in figure. Let ${V_A},{V_B},{V_C}$ be the potentials at points $A,B$ and $C$ respectively. Then
The adjacent diagram shows a charge $+Q$ held on an insulating support $S$ and enclosed by a hollow spherical conductor. $O$ represents the centre of the spherical conductor. and $P$ is a point such that $OP = x $ and $SP = r$ . The electric field at point $P$ will be
The electric field near a conducting surface having a uniform surface charge density $\sigma $ is given by