Two concentric spheres $A$ and $B$ are kept very near to each other. $A$ is negatively charged and $B$ is earthed. The true statement is

$(A)$ Charge on $B$ is zero

$(B)$ Potential at $B$ is zero

$(C)$ Charge is uniformly distributed on $A$

$(D)$ Charge is non uniformly distributed on $A$

Two spheres of radius $R$ and $2R$ having charge $Q$ and $2Q$ respectively are placed far away from each other. How much charge will flow when key $'k'$ is pressed ?

“Electric field inside hollow region of conductor in uniform electric field is same”. Explain.

If electric potential of the inner sphere is $10\, volt$ and that of the outer shell is $50\, volt$ then potential at common centre is :-......$V$

A hollow metal sphere of radius $5\,\, cm$ is charged so that the potential on its surface is $10\,\, V$. The potential at the centre of the sphere is.....$V$

‘At the surface of a charged conductor electrostatic field must be normal to the surface at every point’. Explain.