# Surface charge density

Clancy

## Homework Statement

A sphere with excess charge of 1.5 x10 -7 Coulombs, An outer radius of 2.5cm and inner radius of 1.5 cm ( a cavity ). The question is to find the surface charge density on the inside surface.

I'm totally at a loss on this one and couldn't find how to solve it.

## Homework Equations

Well surface charge density would be C/area of inner sphere.

## The Attempt at a Solution

I couldnt at all figure out how this is done and didnt fiond anythig on it in HRW any help please?