# Help With Gaus's Law

1. Oct 22, 2009

### q3solid

I do not understand these 2 problems at all....

5. a conducting hollow sphere carries a zero net charge. in the center of the sphere there is a point charge of +5.3C. the inner and outer surfaces of the conducting sphere are concentric, and their radius's are 3.2m and 3.7m, respectively. explain why there will be uniform surface charge density on he inner surface, and also on the outer surface, and compute these two surface charge densities.

once again *lost*

6. a point charge q is at the center of a spherical shell of radius R carrying charge 2q spread uniformly over its surface. write expressions for the electric field strength at R/2 and 2R.

once again....*lost*

2. Oct 23, 2009

### Staff: Mentor

Well, one way to work your way out of the *lost* hole, is to list the Relevant Equations. That's why they are requested in the Homework Help Template that you deleted when making your post. Please show us the Relevant Equations, and tell us how you think they may be relevant to the questions.

3. Oct 25, 2009

### q3solid

For number 5, the charge induced on the surface should be equal to the charge that is inducing the charge on the surface. So if you have a charge q in the center, then the inner surface will have a charge -q induced on it. The area of the surface is . The charge density is $$\frac{-q}{4\pi r_{inner}^2}$$ The charge density on the outer surface is $$\frac{q}{4\pi r_{outer}^2}$$

That is my guess.....
and i use the same equation for number 6