What is the potential difference between the plates?

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Discussion Overview

The discussion revolves around calculating the potential difference between the plates of a parallel-plate air capacitor, given its capacitance and charge. Participants explore the implications of changing the plate separation on potential difference and work done, addressing both theoretical and practical aspects of the problem.

Discussion Character

  • Homework-related
  • Mathematical reasoning

Main Points Raised

  • One participant initially calculates the potential difference using the formula V=Q/C but finds their result incorrect and seeks assistance.
  • Another participant suggests checking the arithmetic and requests the original calculation to verify the result.
  • A later reply corrects the initial calculation, providing a new voltage value and discussing the effect of tripling the separation on potential difference.
  • Participants discuss the application of the work formula U=1/2 Q V to find the work required to change the separation, with one participant stating the relationship between final and initial energy.

Areas of Agreement / Disagreement

There is no consensus on the calculations, as participants have different interpretations of the results and methods. The discussion remains unresolved regarding the final work calculation.

Contextual Notes

Limitations include potential errors in arithmetic and assumptions about the relationships between charge, capacitance, and potential difference that may not be fully explored.

Who May Find This Useful

Students and individuals interested in understanding capacitor behavior, electrical potential, and related calculations in physics.

eku_girl83
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Here's my problem:
A parallel-plate air capacitor has a capacitance of 730 picoFarads. The charge on each plate is 2.95 microCoulombs.
a) What is the potential difference between the plates? I used the equation V=Q/C to get 2.4746E-4 V, but this is incorrect.
b)If the charge is kept constant, what will be the potential difference between the plates if the separation is tripled?
I think it would be divided by three.
c) How much work is required to triple the separation?
U=1/2 Q V

I think if I could calculate the potential difference correctly, I could work the rest of the problem. Any hints/help would be welcome!
 
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Check your arithmetic, I do not get the result you posted using the same equation and numbers. Post your calculation.
 
I punched the numbers into the calculator wrong! I now get the voltage equal to 4041.1
Tripling the distance produces a voltage of 3V or 12123.3
Now, how do I apply the equation U=1/2 Q V to find the work required to triple the separation?
 
it would be Uf-Ui=W
 
Thank you! You are all so helpful :)
 

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