Maximum potential given a charge

  • Thread starter c1223
  • Start date
  • #1
2
0

Homework Statement



So the question states that we have a hollow metal sphere of radius 2cm that is charged up. We take the breakdown field of air to be 1MV/m. We are asked to:

a) Calculate the maximum amount of charge which can be placed on the sphere.
b) Calculate the maximum potential on the surface of the sphere.


Homework Equations



[itex]E = \frac{Q}{4\Piε_{0}r^{2}}[/itex]


The Attempt at a Solution



a) [itex]1\cdot10^{6} = \frac{Q}{4\Piε_{0}0.02^{2}}[/itex]
So we get Q as being [itex]4.4\cdot10^{-8}C[/itex]​

However, I'm stuck with what to do next to get the potential. I'm not entirely sure I understand the question? Is it the potential between that space on the surface and the center of the sphere?

I know the answer (or at least it is given as 20kV) but I'm not sure how to arrive at that answer.

Cheers
 

Answers and Replies

  • #2
2
0
I think I might have cracked it. I realised that I also need the equation for potential which is:

[itex]V = \frac{Q}{4\Piε_{0}r}[/itex]

Could someone please explain why it is [itex]r^{2}[/itex] for electric field but [itex]r[/itex] for potential?
 
  • #3
6,054
391
You just need to recall how the potential and the field are related to Coulomb's force.
 

Related Threads on Maximum potential given a charge

Replies
5
Views
7K
  • Last Post
Replies
2
Views
1K
  • Last Post
Replies
5
Views
2K
Replies
1
Views
1K
Replies
18
Views
191
Replies
0
Views
3K
  • Last Post
Replies
4
Views
6K
  • Last Post
Replies
1
Views
6K
Replies
5
Views
3K
Top