Determining the electric potential at a distance

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Homework Statement



The electric potential of a very large isolated flat metal plate is 2000 V. The plate carries a uniform distribution of charge with surface density σ=1 μC/m2. Determine potential V at a distance x=1 cm from the plate. Assume that point x is far from the edges and that x is much smaller than the size of the plate.

Homework Equations



To find the magnitude of the electric field I know I have to use: |E|=σ/2ϵ0

The Attempt at a Solution



I'll be honest I have no clue how to solve this problem, any pointers in the right direction would greatly help!
 

Answers and Replies

  • #2
BruceW
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Well, you've got E, and they are asking for potential, so what equation do you know which connects E and V ?
 
  • #3
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Would I be wrong in stating that since it's a very large plate with uniform charge density, it isn't a point charge. The formula that I have that links those two informations are:

ΔV = -∫Eds, and since the electric field is constant,

ΔV = -Es

ΔV = -σ/2ϵ0 times s

ΔV = -((1 μC/m2)/(2ε0)) times 0.01m

It seems like it's too simple solving like that, I feel like I'm missing something
 
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  • #4
BruceW
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That is the right answer. The question was more simple than you thought. The final step is to use the initial V and change in V to get the V 1cm away.
 
  • #5
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I'm not sure I understand what you mean by that last reply

If I read it right: The answer gives me ΔV, and I have VA, I want VB, right?

So I should do: ΔV = VB - VA ==> ΔV (That I found) = VB - 2000V

So ΔV + 2000V = VB (the volt at 1cm away)?
 
  • #6
BruceW
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yes, that's right.
 

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