A conducting sphere of radius R is given a charge Q. The electric potential and the electric field at the centre of the sphere rrespectively are
zero and ${Q \over {4\pi {\varepsilon _0}{R^2}}}$
${Q \over {4\pi {\varepsilon _0}R}}$ and zero
${Q \over {4\pi {\varepsilon _0}R}}$ and ${Q \over {4\pi {\varepsilon _0}{R^2}}}$
both are zero
