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Electrostatic potential of a circular ring

  • Thread starter KiNGGeexD
  • Start date
317
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I'm a little stumped with this problem, I have posted a photograph below as there is a diagram to compliment the question


ImageUploadedByPhysics Forums1396875812.334406.jpg


Expressions which I used where

V(r)= k q/r

Where q= σ da

Where da is an element of area

And k= 1/4πε


I messed around with these expressions for a while but it didn't really go anywhere I was having trouble defining and element of area (to use spherical coordinates or not).


Any help or suggestions would be great thanks in advanced :):):):)
 
3,729
409
What area? It is a ring. You can consider linear charge density.
 
317
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Ok so area of the circle is

πr^2

And if I'm assuming linear charger density my equation would become


V(r)= k λ/r dl
 
3,729
409
Do you realize that you will have to integrate over the ring? Have you done any similar problems?
 
317
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Yea I realise that but I haven't had a similar problem, most problems have been on the xy plane alone
 
3,729
409
Oh, just now I realized that your point A is on the z axis.
There is an "a" in the xy plane that misled me.

Then is is much simpler than I thought.
If you take a small element of ring with length dl, what will be the charge on this element?
What will be the distance between this element and the point A?
 
317
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What I mean is it was a two dimensional problem where lines were the only consideration rather than areas or volumes
 
3,729
409
Oh, here it's the same too. It has nothing to do with areas or volumes.
 
317
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The distance between the two points would be


(z^2+ x^2)^1/2
 
317
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Would I just use my distance and integrate from -a to a, or rather multiply by 2 and integrate from 0 to a?
 
Just one hint!!!
Distance between point A and any point on ring is constant (Pythagoras Theorem - hehe).
Take an element dq on the ring. You must know the expression of potential due to a point charge.
You'll get an integral. ∫ dq = Q :eek:
The answer will come in terms of total charge of ring.
 
3,729
409
The last post was from 2014.
 

PeroK

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With any luck the OP has graduated by now.
 
Not every single person in this world has graduated. Others might have the same query. Right?
 
3,729
409
So when you say "you" you mean a generic person (who did not graduate) and not the OP. :) It looked like you were answering the question the OP asked in April 2014, right above your answer.
 

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