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1. The problem statement, all variables and given/known data

A parallel-plate capacitor 0.5m by 1.0m has a separation distance of 2cm and a voltage difference of 10V. Find the stored energy, assuming that ε=εo. If a 200-volt potential is applied in the capacitor, (a) determine the energy stored; (b) hold d1 at 2cm and the voltage difference at 200V, while increasing d2 to 2.2cm, determine the final stored energy.

2. Relevant equations

U=(1/2)(CV^{2})

C=εS/d

3. The attempt at a solution

(a)

C=((8.854x10^{-12})(0.5x1.0))/(0.02)

C=2.2135x10^{-10}F

U=(1/2)(2.2135x10^{-10})((10+200)^{2})

U=4.8808x10^{-6}J

(b)

C=((8.854x10^{-12})(0.5x1.0))/(0.022)

C=2.0123x10^{-10}F

U=(1/2)(2.0123x10^{-10})((10+200)^{2})

U=4.4371x10^{-6}J

I'm not sure what to do with the voltage difference of the capacitor, so I added it with the voltage potential applied.

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# Homework Help: Electromagnetics - parallel plate capacitor energy storage

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