A charge $q$ is placed at the centre of cubical box of side a with top open. The flux of the electric field through one of the surface of the cubical box is
zero
$q/{\varepsilon _0}$
$q/{6\varepsilon _0}$
$5q/{6\varepsilon _0}$
A metallic shell has a point charge $'q'$ kept inside its cavity. Which one of the following diagrams correctly represents the electric field lines
Two equal negative charges $-q$ are fixed at points $(0, -a)$ and $(0, a)$ in the $x-y$ plane. A positive charge $Q$ is released from rest at a point $(2a, 0)$. The charge $Q$ will
A spherical shell with an inner radius $'a'$ and an outer radius $'b'$ is made of conducting material. A point charge $+Q$ is placed at the centre of the spherical shell and a total charge $-q$ is placed on the shell. Final charge distribution on the surfaces as
The force on a charge situated on the axis of a dipole is $F$. If the charge is shifted to double the distance, the new force will be
If potential at centre of uniformaly charged ring is $V_0$ then electric field at its centre will be (assume radius $=R$ )