# Charge density in cylinder with uniform charge

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1. Feb 28, 2015

### p0ps1c1e

1. A charge density ρ (charge per unit volume) is distributed uniformly throughout a non-conducting cylinder of radius R. What is the magnitude of the electric field a distance r = R/2 from the cylinder's axis?

2. Relevant equations

E ∫dA = q(interior)/ε0

3.

So I tried doing EA = (ρA)(v/V)/ε0 where v is the volume of the Gaussian surface and V is the volume of the cylinder

E = (ρ*(πR^2L/4πR^2L))/ε0
E = ρ/4ε0

However the answer is supposed to be E = ρR/4ε0

I'm not sure where I'm going wrong

2. Feb 28, 2015

### BvU

Check Gauss law once more: one is a volume (to determine q(interior) ) and the other is an area (of the surface).