A metal sphere of radius 10 cm is given a charge of `12muC`. The force acting on unit area of its surface is

Options

A. `5.151xx10^(2)N//m^(2)`
B. `5.15xx10^(3)N//m^(2)`
C. `515xx10^(-2)N//m^(2)`
D. `5.15xx10^(-3)N//m^(2)`

Answer

A

Explanation

`f=sigma^(2)/(2in_(0)k)=q^(2)/(2in_(0)kds^(2))`
`=q^(2)/(32in_(0)kpi^(2)R^(4))" "(thereforeds=4piR^(2))`
`=((12xx10^(-6))^(2))/(32xx8.85xx10^(-12)xx1xx9.87xx(10^(-1))^(4))`
`=5.151xx10^(2)N//m^(2)`