A parallel plate air capacitor has a plate separation of $5\;mm$ and is charged to a potential difference of $400\; V$. Calculate the energy density in the region between the plates.

Given,
Distance between plates $(d) = 5\;mm = 5 \;*\;10^{-3}\;m$
Potential difference $(V) = 400\;V$
Energy Density $(u) = ?$

We have,

$u = \frac{1}{2}\,*\; \epsilon_0\, E^2 = \frac{1}{2}\,*\,(\frac{V}{d})^2 = \frac{1}{2}\;*\;8.85\;*\;10^{-12}\;*\;(\frac{400}{5\;*\;10^{-3}})^2$ 

$ = 0.028\;J/m^3$

∴ Energy Density $(u) = 0.028\; J/m^3$

Return to Main Menu