Electric field between two oppositely charged parallel plates:

In the last article, I have explained and derived the expression for the capacitance of parallel plate capacitor with dielectric and without dielectric. Today we will discuss and derive the relation for electric field between two oppositely charged parallel plates.

Let +q and –q be the charges on the plates of a parallel plate air capacitor. Let A be the area of the plate.

The magnitude of the electric field, E, between the parallel plates

is given by

E1 = q/ ε₀A

If  σ is the charge per unit area, then q = Aσ and thus

E1 = σ/ ε₀

This is the expression for the electric field between two oppositely charged parallel plates.