Q: A conducting sphere of radius R is given a charge Q. The electric potential and the electric field at the centre of the sphere respectively are
$\displaystyle (a) Zero \; and \frac{Q}{4\pi \epsilon_0 R^2} $
$\displaystyle (b) \frac{Q}{4\pi \epsilon_0 R} \; and \; Zero$
$\displaystyle (c) \frac{Q}{4\pi \epsilon_0 R} \; and \; \frac{Q}{4\pi \epsilon_0 R^2}$
(d)both are zero
Ans: (b)
Sol: For a conducting sphere, electric potential at the centre of sphere is same as that on the surface of sphere
$\displaystyle = \frac{Q}{4\pi \epsilon_0 R} $
The electric field intensity at a point inside the conducting sphere is zero.