Q19. What is the Stored Energy on a Capacitor Charged to 200 V?

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SUMMARY

The stored energy in a capacitor charged to 200 V with a capacitance of 20 F is calculated using the formula u = 0.5CV², resulting in 0.4 J. A common error arises when the capacitance is misinterpreted; if the capacitance were actually 20 µF, the stored energy would be significantly lower. The discussion highlights the importance of unit clarity in capacitor problems, particularly distinguishing between Farads and microfarads.

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Homework Statement


Q18. A 20 F capacitor is charged to 200 V. Its stored energy is:
C. 0.4 J


Homework Equations


q = CV
u = .5CV^2


The Attempt at a Solution


I tried plugging in the numbers and got 1.6E6, which isn't even close to the answer. I really don't know where to go with this one. I even went and found an energy calculator online and it came up with the same answer I got. Is stored energy not the potential energy of the capacitor?
 
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Hi Strawberry,

Are you sure the capacitance wasn't 20 \mbox{ }\mu F? Most capacitors that I've dealt with in problems are in that range, and that would also give the answer you are given.
 
I guess the symbol just didn't show up in the .pdf. Thanks again alphysicist, you've cleared up a ton of things for me in the past few weeks.
 
Sure, I'm glad I could help!
 

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