The inward and outward electric flux for a closed surface in units of $N{\rm{ – }}{m^2}/C$ are respectively $8 \times {10^3}$ and $4 \times {10^3}.$ Then the total charge inside the surface is [where ${\varepsilon _0} = $ permittivity constant]

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

Using thomson's model of the atom, consider an atom consisting of two electrons, each of charge $-e$, embeded in a sphere of charge $+2e$ and radius $R$. In equilibrium each electron is at a distance $d$ from the centre of the atom. What is the equilibrium separation between electrons

A long cylindrical volume contains a uniformly distributed charge of density $\rho \;Cm ^{-3}$. The electric field inside the cylindrical volume at a distance $x =\frac{2 \varepsilon_{0}}{\rho} m$ from its axis is $…….Vm ^{-1}$

A charge $Q$ is enclosed by a Gaussian spherical surface of radius $R$. If the radius is doubled, then the outward electric flux will