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

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Homework Help Overview

The problem involves calculating the stored energy in a capacitor charged to 200 V, with a stated capacitance of 20 F. The original poster expresses confusion regarding their calculation and the expected answer.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to calculate the stored energy using the formula for energy in a capacitor but arrives at a significantly different result than expected. They question whether their understanding of stored energy as potential energy is correct.
  • One participant suggests reconsidering the capacitance value, proposing that it might be 20 μF instead of 20 F, which could align with the expected answer.

Discussion Status

The discussion is ongoing, with participants exploring the implications of the capacitance value and its impact on the stored energy calculation. There is no explicit consensus, but a suggestion has been made that could clarify the original poster's confusion.

Contextual Notes

The original poster's calculation appears to be based on a potentially incorrect capacitance value, which is under discussion. The context of the problem is framed within a homework assignment, which may impose specific constraints on the approach taken.

Strawberry
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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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