Question

A `5.80 muF` parallel-plate air capacitor has a plate separation of `5.00 mm` and is charged to a potential difference of `400 V`. Calculate the energy density in the region between the plates, in `J/m^3`
A. `0.113`
B. `0.117`
C. `0.152`
D. none of these

Answer 1

Correct Answer - B
`A=90 cm^(2),d=2 mm`
`E=V/d,V400V`
`u=1/2epsilon_(0)E^(2)=1/2=1/2epsilon_(0)(V/d)^(2)`
`=1/2(8.85x10^(-12))((400)/(2xx10^(-3)))^(2) =0.177 Jm^(-3)`.