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Capacitors and resistor question?
When the 1000 microF capacitor is fully charged, it is removed from the circuit and connected across a 10 ohm resistor. What is the total energy dissipated in the resistor? (V=9V).
Not sure if I just use E=1/2 CV^2.
Thanks
1 Answer
- MohasaLv 41 decade agoFavorite Answer
Short answer: yes, E = 1/2 CV^2 is the total energy dissipated in the resistor.
Basically, you're discharging the capacitor via a resistor. With time, all the energy
stored in the capacitor in the electric field is dissipated via the resistor. The equation
you gave is the total energy stored in the capacitor.
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If you're up to the task, you can prove it!
From P = IV, and E = Pt
or dE = Pdt = IVdt = V²/R dt
This integration is done from t=0 to t = infinity.
Use V = Vp*exp(-t/RC) and
E = ∫{Vp*exp(-t/RC)}²/R dt
to establish that
E = Vp²C/2, Vp is the peak (fully charged) voltage across the
capacitor (resistor as well).
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Hope this helps