Electric field due to an infinite,straight,uniformly charged wire varies with distance $r$ as:

$A$ solid metal sphere of radius $R$ having charge $q$ is enclosed inside a concentric spherical shell of inner radius $a$ and outer radius $b$ as shown in the figure. The approximate variation of the electric field $\overrightarrow{E}$ as a function of distance $r$ from the centre $O$ is given by:

$A$ negatively charged plate has a surface charge density of $\sigma = 2 \times 10^{-6} \ C/m^2$. An electron with kinetic energy $KE = 200 \ eV$ is projected towards the plate. If the electron does not strike the plate,find the minimum initial distance $r$ in $mm$ from the plate.

Two infinite parallel metal planes contain electric charges with charge densities $+\sigma$ and $-\sigma$ respectively,and they are separated by a small distance in air. If the permittivity of air is $\varepsilon_{0}$,then the magnitude of the field between the two planes with its direction will be:

$A$ thin metallic spherical shell of radius $r$ contains a charge $Q$ on its surface. $A$ point charge $q_1$ is placed at the centre of the shell and another charge $q_2$ is placed outside the shell at a distance $x$ from the centre. Then, the forces on charges $q_1$ and $q_2$ respectively are

The figure shows a hollow hemisphere of radius $R$ in which two charges $3q$ and $5q$ are placed symmetrically about the centre $O$ on the planar surface. The electric flux over the curved surface is