# Can someone answer a quick question for me about e field by spheres.

1. Sep 5, 2011

### charlies1902

So let's say a sphere has radius R and you want to find the e field where R>r and R is equal to or greater than r.

would the e field for R>r just be 0?
Wouldn't that also mean it's 0 for R is equal to or greater than r, or does it change because it's EQUAL or greater?

2. Sep 5, 2011

### vela

Staff Emeritus
The answers depends on how the charge is distributed through the solid sphere.

3. Sep 5, 2011

### charlies1902

sorry, uniformly distributed thorughout the sphere.

4. Sep 5, 2011

### vela

Staff Emeritus
OK, in that case, the electric field wouldn't be 0 inside the sphere. You can calculate what it is by applying Gauss's Law.

5. Sep 6, 2011

### charlies1902

i think i got the sphere confused with spherical shell because in the book it keeps switching back and forth. For spherical spheres it would be 0 right for points within the sphere?

6. Sep 6, 2011

### vela

Staff Emeritus
Yes, if all the charge is on uniformly distributed on the surface of the sphere, there's no electric field inside.