Question

A parallel plate capacitor of capacitance \[ 12\,\mu\text{F} \] is charged to a potential of \[ 180\,\text{V}. \] If the distance between the plates of the capacitor is \[ \frac{3}{\sqrt{\pi}}\ \text{mm}, \] then the energy density of the electric field between the plates is

• A. \[ 25\times10^{-6}\ \text{Jm}^{-3} \]
• B. \[ 25\times10^{-3}\ \text{Jm}^{-3} \]
• C. \[ 50\times10^{-6}\ \text{Jm}^{-3} \]
• D. \[ 50\times10^{-3}\ \text{Jm}^{-3} \]

Hint:

The energy density of an electric field depends only on the field strength: \[ u=\frac12\varepsilon_0E^2. \] For a parallel plate capacitor, \[ E=\frac{V}{d}. \] Notice that capacitance is not required once \(V\) and \(d\) are known.

Answer 1

The Correct Option is D