Question

A metallic spherical solid ball of radius $r$ has capacitance ${}^{\prime }{C}^{\prime }$ , then metallic spherical hollow ball of radius $2r$ has capacitance equal to

• A. $0$
• B. $2C$
• C. $C/2$
• D. $2C/3$

Answer 1

The correct option is B $2C$

Capacitance of spherical ball whether solid of hollow is $4\pi ϵr$.
$\frac{C^{\prime }}{C}=\frac{4\pi ϵ\left(2r\right)}{4\pi ϵr}=2$

$C^{\prime }=2C$