Solid insultaing sphere electric field

[odyssey4001]

Homework Statement

A solid insulating sphere of radius R carries a charge per unit volume of p. Use Gauss' law to find an expression for the eletric field on a spherical surface of radius R/2 ie: inside the sphere.

Homework Equations

Gauss' Law = (Net Flux = Q / Eo)

Volume of a Sphere = (4/3)(pi)(R^3)

The Attempt at a Solution

I simply combined Gauss' Law and the volume of the sphere to get,

E = (4Q) / [(3)(pi)(Eo)((R/2)^3)]

That seems to easy though have I missed something?

 

[Doc Al]

I simply combined Gauss' Law and the volume of the sphere to get,

E = (4Q) / [(3)(pi)(Eo)((R/2)^3)]

Not sure what you did here. What's Q? Express the charge within the gaussian surface in terms of ρ. How do you calculate the flux?