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## Homework Statement

A hollow metal sphere has inner and outer radii of 20.0 cm and 30.0 cm, respectively. As shown in the figure, a solid metal sphere of radius 10.0 cm is located at the center of the hollow sphere. The electric field at a point P, a distance of 15.0 cm from the center, is found to be E1 = 1.53·104 N/C, directed radially inward. At point Q, a distance of 35.0 cm from the center, the electric field is found to be E2 = 1.53·104 N/C, directed radially outward.

Image of the problem: http://postimg.org/image/6cnneik69/

a) Determine the total charge on the surface of the inner sphere.

b) Determine the total charge on the surface of the inner surface of the hollow sphere.

c) Determine the total charge on the surface of the outer surface of the hollow sphere.

## Homework Equations

∫∫[itex]\vec{E}[/itex] * [itex]\vec{dA}[/itex] = [itex]\frac{q_{enc}}{E_{0}}[/itex]

## The Attempt at a Solution

For part (a), I believe that the charge on the inner sphere from point P would be negative, since it is directed radially inward, while the charge on the inner sphere from point Q would be positive.

If I plug in the values into the equation above, then add them together, would I arrive at the correct answer?

I am still working on part (b) and (c), but want to make sure that I've set up part (a) correctly first.