If the electric flux entering and leaving an enclosed surface is $\phi_1$ and $\phi_2$ then charge enclosed in the surface is ($\varepsilon_0=$ permittivity of free space)

Two surfaces A and B are enclosing the charges as shown below. The total normal electric induction (T.N.E.I) through the surfaces A and B are respectively.

A spherical rubber balloon carries a charge, uniformly distributed over the surface. As the balloon is blown up and increases in size, the total electric flux coming out the surface

If a $10 \mu \mathrm{C}$ charge exists at the centre of a square, the work done in moving a $2 \mu \mathrm{C}$ point charge from corner A to corner B of a square ABCD is