A metallic sphere of radius 18 cm has been given a charge of `5xx10^(-6)C.` The energy of the charged conductor is

Options

A. `0.2J`
B. `0.6J`
C. `1.2J`
D. `2.4J`

Answer

B

Explanation

Here ` r= 18 cm = 18 xx 10^(-2) m , q = 5 xx 10^(-6)C`
As `C = 4 pi epsi_(0)r =(18 xx 10^(-2))/(9 xx 10^(9)) = 2 xx 10^(-11) F`
Energy of charged conductor is
`U = (q^(2))/(2C) = ((5 xx 10^(-6))C)/(2 xx 2 xx10^(-11)F) = 0.625 J`