A variable condenser is permanently connect to a `100V` battery. If the capacity is charged from `2muE` to `10muF`, then change in energy is equal to

Options

A. `2 xx 10^(-2) J`
B. `2.5 xx 10^(-2)J`
C. `3.5 xx 10^(-2)J`
D. `4 xx 10^(-2)J`

Answer

D

Explanation

`DeltaU = U_(2) - U_(1) = (V^(2))/(2) (C_(2) - C_(1))`
`= ((100)^(2))/(2) (10 - 2) xx 10^(-6) = 4 xx 10^(-2) J`