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The plates of a parallel plate capacitor...

The plates of a parallel plate capacitor have an area of 90 `cm^2` each and are separated by 2.5 mm. The capacitor is charged by connecting it to a 400 V supply.
(a) How much electrostatic energy is stored by the capacitor?
(b) View this energy as stored in the electrostatic field between the plates, and obtain the energy per unit volume u. Hence arrive at a relation between u and the magnitude of electric field E between the plates.

Text Solution

Verified by Experts

Capacitance of a parallel plate capacitor
` C = (epsi_0A)/(d) = (8.85xx10^(-12) xx99xx10^(-4))/(2.5 xx 10^(-3))`
` = 3.186 xx 10^(-11) F`
Energy of the capacitor
` = (1/2) CV^2`
` = 1/2 xx 3.186 xx 10^(-11) xx (400)^2`
Energy ` = 2.55 xx 10^(-6) J`
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