# What is the Electric Field inside this charged sphere?

## Homework Statement

Let me just put this here:
http://i.imgur.com/dgcWAC3.png

.

## Homework Equations

E_flux=EA=(q_encl)/(permittivity)
Area=4pir^2

## The Attempt at a Solution

Whenever I manipulate the above equations, I get a term of the form R/r, which implies, R being 5 cm, and r being the radius inside. This implies that the field goes to infinity at the center, when I'm pretty sure by spherical symmetry it is 0!

## Answers and Replies

Doc Al
Mentor
Whenever I manipulate the above equations, I get a term of the form R/r, which implies, R being 5 cm, and r being the radius inside.
Not sure how you'd get an expression with R = 5 cm, when evaluating the field at r = 4 cm. Using Gauss' law at r = 4 cm gives you the field at that point, assuming spherical symmetry. What's the enclosed charge at that radius?

when I'm pretty sure by spherical symmetry it is 0!
That's true and Gauss' law agrees.