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

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A 20 F capacitor charged to 200 V has a stored energy of 0.4 J, calculated using the formula u = 0.5CV^2. One participant initially calculated the energy as 1.6E6 J, indicating a misunderstanding of the capacitance value. The discussion suggests that the correct capacitance might be 20 µF instead of 20 F, which aligns with typical values encountered in similar problems. Clarification on the units of capacitance is essential for accurate calculations. The conversation emphasizes the importance of unit conversion in capacitor energy calculations.
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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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