Study guide asked/stated: A 100 microF capacitor has 100 V across it terminals, A 100 ohm(adsbygoogle = window.adsbygoogle || []).push({});

resistor is placed across these terminals. How much energy is lost when the voltage is dropped to 50V?

I answered with w= 1/2 CV^2, 1/2*100*10E-6*100^2

= .5 J

Book says w = 25 * 10-6 * 10^4.

= .25 J

(next step is to calculate energy at 50V). Where did the 25 come from?

Hope this is the right forum (and not already asked and answered).

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# Homework Help: Calculating Energy (capcitor study)

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