Two large, thin metal plates are parallel and close to each other. On their inner faces, the plates have surface charge densities of opposite signs and of magnitude 17.0 × 10⁻²² C/m². What is E: (a) in the outer region of the first plate, (b) in the outer region of the second plate, and (c) between the plates?

Imagine the situation as under:

A and B are two parallel plates close to each other.

Outer region of plate A is labelled as I, outer region of plate B is labelled as III, and the region between the plates, A and B, is labelled as II.

Charge density of plate A, σ = 17.0 x 10^-22 C/m²

Charge density of plate B, σ = -17.0 ^x 10^–22 C/m²

In the regions, I and III, electric field E is zero. This is because charge is not enclosed by the respective plates.

Electric field E in region II is given by the relation,

E = σ /ε₀ 

Where,

ε₀  = Permittivity of free space = 8.854 x 10⁻¹² N^_1C²m²

E = (17.0 x 10^–22)/ (8.854 x 10⁻¹²)

= 1.92 x 10^-10 N/C

Therefore, electric field between the plates is 1.92 x 10^-10 N/C