Am I missing something? (stored energy U=.5QV)

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Homework Help Overview

The problem involves calculating the energy stored in a capacitor with given charge, potential difference, and plate separation. The subject area is related to electrostatics and capacitance.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to use the formula U = 0.5QV to find the energy stored but questions the relevance of the plate separation distance. Another participant offers reassurance regarding the calculations, although there is a correction regarding the charge value.

Discussion Status

The discussion is ongoing, with participants clarifying calculations and addressing potential misunderstandings about the problem's parameters. There is acknowledgment of a correction needed in the charge value, but no consensus on the necessity of the plate separation in the calculation.

Contextual Notes

The original poster notes that typically all provided data should be relevant, raising questions about the role of the plate separation distance in the context of the problem.

runran
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So there's this problem where they provide charge on each plate of .02E-9 Coulombs with a potential difference of 240 V. Parallel plates separated by .0004m air. Asks for energy stored in capacitator. I used U=.5QV equation to get 2.4E-6 J but didn't use the .0004 constant at all. Did I miss something in what calculation I'm supposed to be doing? Usually data isn't provided in a problem unless it's supposed to be used, but I can't think of how I would need that. Thank you.
 
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runran said:
So there's this problem where they provide charge on each plate of .02E-9 Coulombs with a potential difference of 240 V. Parallel plates separated by .0004m air. Asks for energy stored in capacitator. I used U=.5QV equation to get 2.4E-6 J but didn't use the .0004 constant at all. Did I miss something in what calculation I'm supposed to be doing? Usually data isn't provided in a problem unless it's supposed to be used, but I can't think of how I would need that. Thank you.

Your logic is correct, however you calculations are not. The energy stored is by my calculations is 2.4 x 10-9 J.

~H
 
Woops, meant to put Q as .02E-6 c
But thanks Hootenanny for the reassurance that the solution is okay.

A cookie for you (::)
 
runran said:
A cookie for you (::)

Why thank you old chap :biggrin:

~H
 

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