(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A coaxial transmission line has an inner conducting cylinder of radius a and an outer conducting cylinder of radius c. Charge ql per unit length is uniformly distributed over the inner conductor and -ql over the outer. If dielectric [itex]\epsilon_{1}[/itex] extends from r=a to r=b and dielectric [itex]\epsilon_{2}[/itex] from r=b r=c, find the electric field for r<a, for a<r<b, for b<r<c and for r>c. Take the conducting cylinders as infinitesimally thin.

2. Relevant equations

3. The attempt at a solution

For r<a there is no charge enclosed thus the flux is 0 so E is also 0

Here is the solution they give for a<r<b. (see figure attached)

I am confused as to how he determines the components of the vector [itex]d\vec{S}[/itex]. Is there a picture that will explain this?

Thanks again!

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# Flux out of a Cylindrical Cable

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