Question

The spherical conductor of radius 12 cm has a charge of 1.6 x 10^-7 C distributed uniformly on its surface. What is the electric field (a) inside the sphere, (b) just outside the sphere (c), at a point 18 cm from the centre of the sphere?

Answer 1

R = 12 x 10^-2 m, Q = 1.6 x 10^-7C
(a) Zero

(b) E = \(\frac{9 \times 10^{9} \times 1.6 \times 10^{-7}}{\left(12 \times 10^{-2}\right)^{2}}\)
= \(\frac{9 \times 10^{9} \times 1.6 \times 10^{-7}}{12 \times 12 \times 10^{-4}}\)
= 10⁵ NC^-1

(c) Here R= 18 x 10^-2m
Hence E = \(\frac{9 \times 10^{9} \times 1.6 \times 10^{-7}}{18 \times 18 \times 10^{-4}}\)
= \(\frac { 4 }{ 9 }\) x 10⁵ ≈ 4.4 x 10⁴ NC^-1