Question

Taking earth to be a metallic spheres, its capacity will approximately be 

(A) 6.4 × 10⁶F 

(B) 700PF 

(C) 71μF 

(D) 700pF

Answer 1

The correct option (C) 711μF

Explanation:

for a sphere, c = 4π∈­₀R

c = [1/(9 × 10⁹)] × 6400 × 10³

as [1/(4∈₀)] = 9 ×10⁹ & R = Radius of earth = 6400 km

∴ c = 7.11 × 10^–4 F

c = 711 × 10^–6 F

c = 711μF