# Electric flux and electric fields

1. Jul 13, 2008

### aiaigasa

Hi, I'm having a bit of trouble with the following problem. Any insight as to what I'm doing wrong?

1. The problem statement, all variables and given/known data

A solid metal sphere with radius 0.900 m carries a net charge of 0.130 nC. Find the magnitude of the electric field at at a point inside the sphere, 0.100 m below the surface.

2. Relevant equations

$$\Phi = \int\vec{E}\cdot\vec{A} = \frac{Q}{\epsilon_{0}}$$

3. The attempt at a solution

$$Q = \frac{0.130 \times 10^{-9}}{\frac{4}{3}\pi(0.9)^{3}} \times \frac{4}{3}\pi(0.8)^{3} = 9.13032 \times 10^{-11}$$
$$\Phi = \frac{9.13032 \times 10^{-11}}{\epsilon_{0}} = 10.3119$$
$$E = \frac{\Phi}{A} = \frac{10.3119}{4\pi(0.8)^{2}} = 1.28217 \frac{N}{C}$$

Last edited: Jul 13, 2008
2. Jul 13, 2008

### Defennder

What can you deduce about a charged conductor under electrostatic equilibrium?