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.