# Total Charge (Spheres and Potential)

1. Oct 10, 2008

### jrc5135

1. The problem statement, all variables and given/known data
A conducting sphere of radius a, at potential V0, is surrounded by a thin concentric spherical shell of radius b over which someone has glued a surface charge. sigma = kcos(theta) where k is a constant

i know V(r, theta) and induced surface charge on the conductor

2. Relevant equations

Q = integral (sigma) da

3. The attempt at a solution
trying to use equation 1 but i'm not sure first off the limits on r for each

2. Oct 10, 2008

### gabbagabbahey

da is the infinitesimal area element of the surface...the entire surface is at r=b....what is your expression for da?

3. Oct 10, 2008

### jrc5135

but what about the charge coming from the inner sphere at Vo my da is going to rdrdtheta

4. Oct 10, 2008

### gabbagabbahey

why is there a dr term in your da, isn't r constant over a spherical surface?

Are you trying to compute the total charge on the outer shell, or the conductor, or both?

5. Oct 10, 2008

### jrc5135

trying to find the charge for both

6. Oct 10, 2008

### gabbagabbahey

Well, you'll have to compute the charge of each individually and then add them up.