# Homework Help: Electric field outside of conducting sphere.

1. Jun 13, 2010

### ramses07

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

A conducting sphere of radius 0.01 m has a charge of 1.0 × 10–9 C deposited on it. The magnitude of the electric field in N/C just outside the surface of the sphere is

2. Relevant equations
E=kq/r^2

EA=q/eo

3. The attempt at a solution

I tried the first equation and got 90000, but the answer is 900. Im racking my brains here trying to understand how to find the answer. Its seems simple enough, im probably just missing a step, can anybody point to what im doing wrong.

2. Jun 14, 2010

### Axiom17

Could you show your calculations so far? Then can see where you're going wrong.

3. Jun 14, 2010

### hikaru1221

Does the question mention the permittivity of the medium outside the sphere?

4. Jun 14, 2010

### Axiom17

..also I got $E=90000NC^{-1}$ as well. Where did you get that the answer should be $E=900NC^{-1}$? Also check those values you've been given are correct (but they seem OK).