# Electric Field in a cylindrical Coaxial Capacitor

## Homework Statement

Two infinite coaxial metal cylindrical tubes of radius a and b (a < b) are charged
with charge per unit length (unit [C/m]) $$\lambda$$ and $$-\lambda$$ respectively.

Calculate the electric field between the tubes (i.e. for a < r < b)

Where $$\epsilon_{0}$$ is the permittivity of free space
2. The attempt at a solution

Considering a Gaussian surface with radius R & length L where a < R < b, we can use Gauss' law to find the enclosed charge;

$$\oint \vec{E}. d\vec{a} = \frac{ q_{enc}}{\epsilon_{0}}$$

This can then be rewritten as;

$$\oint \vec{E}. d\vec{a} = \frac{\lambda L}{\epsilon_{0}}$$

Then I have no clue of where to go. Can take the magnitudes of the vectors and take the E outside or do i have to do something different?

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