Two point charges of magnitudes $-8 \mu \mathrm{C}$ and $+32 \mu \mathrm{C}$ are separated by a distance of 15 cm in air. The position of the point from $-8 \mu \mathrm{C}$ charge at which the resultant electric field becomes zero is

Two positive point charges are separated by a distance of 4 m in air. If the sum of the two charges is $36 \mu \mathrm{C}$ and the electrostatic force between them is 0.18 N , then the bigger charge is

A hollow spherical shell of radius $r$ has a uniform charge density $\sigma$. It is kept in a cube of edge $3 r$ such that the centres of the cube and the shell coincide. Then the electric flux coming out of one face of a cube is ( $\varepsilon_0=$ permittivity of free space)

If the electric potential at a point on the surface of a hollow conducting sphere of radius $R$ is $V$, then the electric potential at a point which is at distance $R / 3$ from the centre of the sphere is