Question

I'm trying to calculate the capacitance of a capacitor, partially filled with a dielectric. When you calculate the electric field strength of the electric field gap, why is it sigma/epsilon zero

Answer 1

Professor Lewin has an outstanding lecture on Gauss' Law on OpenCourseWare. That should explain it better than any diagram I could draw.

Answer 2

For an infinite pair of parallel plates with surface charge density sigma, the electric field between the plates is sigma/ epsilon zero.

You can use Gauss's Law to show this. Have a look at this HyperPhysics webpage:

http://hyperphysics.phy-astr.gsu.edu/hbase/electric/elesht.html

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