A parallel plate capacitor of capacitty `100 mu F` is charged by a battery at `50` volts. The battery remains connected and if the plates of the capacitor are separated so that the distance between them is halved the original distance, the additional energy gives by the battery to the capacitor in Joules is .....

Options

A. `125xx10^(-3)`
B. `12.5xx10^(-3)`
C. `1.25xx10^(-3)`
D. `0.125xx10^(-3)`

Answer

A

Explanation

`E_(1)=(1)/(2)C_(1)V^(2), E_(2)=(1)/(2)C_(2)V^(2), C_(2)=2C_(1)`
`therefore C=(C_(2)C_(3))/(C_(2)+C_(3))+C_(1)`