Question

Capacity of an isolated sphere is increased n times when it is enclosed by an earthed concentric sphere. The ratio of their radii is –

• A. $\frac{n^{2}}{n - 1}$
• B. $\frac{n}{n - 1}$
• C. $\frac{2n}{n + 1}$
• D. $\frac{2n + 1}{n + 1}$

Answer 1

Answer: (B)

$\frac{n}{n - 1}$

Answer 2

C₁ = 4pe₀R₁

and C₂ = 4pe₀

Given that C₂ = nC₁

or = nR₁

or $\frac { \mathrm { R } _ { 2 } / \mathrm { R } _ { 1 } } { \mathrm { R } _ { 2 } / \mathrm { R } _ { 1 } - 1 }$ = n

or =