A parallel plate capacitor is connected to a battery. The plates are pulled apart with uniform speed. If x is the separation between the plates, then the rate of change of electrostatic energy of the capacitor is proportional to

Options

A. `x^(-2)`
B. x
C. `x^(-1)`
D. `x^2`

Answer

A

Explanation

`U=1/2CV^2=1/2((Aepsilon_0)/x)V^2`
`implies (dU)/(dt)=1/2epsilon_0AV^2[-1/x^2 (dx)/(dt)] implies (dU)/(dt) prop x^(-2)`