Finding electric potential between two concentric spheres.

  • #1
2
0

Homework Statement


A spherical shell with inner radius A and outer radius 3A which has a uniform charge density, i.e charge per unit volume, p0. Find difference in electric potential between the center of the shell and a point a distance 2A from the center.



Homework Equations


The answer given is. -(p0A2)/3ε0

The Attempt at a Solution


I am completely lost as to what I'm supposed to do here. I would think you'd find the potential at 2A and subtract it from that at the center. But how exactly do you do that?
I integrated the elctric field due to a charged sphere along 2A to A. So that makes:
∫E dr= ∫(ρr)/3ε0)dr=V
That makes:

[(ρr2)/6ε)] from 2A to A which does not equal the answer.
I think I'm stumped here. Any help would be greatly appreciated!
 

Answers and Replies

  • #2
TSny
Homework Helper
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Welcome to PF!

Your expression for the electric field does not look correct. E for a uniformly charged shell is different than E for a uniformly charged solid sphere.
 
  • #3
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I was not aware of the difference. I'll look it up.
 
  • #4
TSny
Homework Helper
Gold Member
13,161
3,462
I'll look it up.
Or, apply Gauss' law to find E inside the shell.
 

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