# Electric potential

1. Jan 19, 2007

### stunner5000pt

1. The problem statement, all variables and given/known data
A charge q sits in a spherical hollow inside a spherical conductor.

q is located at r=0
Hollow from r = 0 to r =a
from r=a to r=b a conductor
r=b to r = infinity free space

Find the potential everywhere
2. The attempt at a solution
I calculated these
$$E = \frac{1}{4 \pi \epsilon_{0}} \frac{q}{r^2} \hat{r}$$
for r<a and r> b

E= 0 for a<r<b

To find the potential from 0 to r=a is what concerns me... We end up having hte potential blow up in at the origin.

it is late and im not thinking striaght but i cant see a way out ....

please help!

2. Jan 19, 2007

### chanvincent

Your answer is correnct.... Good job....

That is absolutely normal for a point charge, That is the reason why we have to
DEFINE V = 0 at r = infinity instead of r = 0

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