Q on Spherical Shell

[foolishone]

A spherical shell has inner radius R-in and outer radius R-out. The shell 
contains total charge Q, uniformly distributed. The interior of the shell is 
empty of charge and matter.

Find the magnitude of the electric field within the shell, R-in <= r <= R-out.

 

Basically find the E-f within the sphere.

 

I don't really think I understand it. The charge lies all on the exterior, so the interior surface must have -Q. I have tried several different answers, but they say that it depends on R-in and, I assume R-out. I know its a Gauss problem and E = Q/A*e-0, but I am having trouble finding the Q. Do I find the volume density of the big sphere and multiply it by the volume of the Gaussian sphere? Any help?

 

Thanks!

 

 

EDIT:

 

Well...I guess just talking about it 'out loud' helped alot.

 

I realized I was on the right track by getting the volume of the shell (the R-out minus R-in) and putting that under the Q to get a volume charge density, then multiplying that by whatever volume I wanted, which was the volume at my 'r' minus the volume of R-in. Put that over A*e-0 and voila!

 

Anyway...thanks...even though you didn't do much.

[Klaynos]

Yep your method seems to work

 

Guass's law ROCKS Got to love the maxwell equations