Question

Two charges 10nC and -4nC are placed at points (5cm,0,0) and (23cm,0,0) in a region of space where there is no other external field. What is the electrostatic potential energy at this charge system?

Answer 1

Answer:

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=17.0×10−22C/m2

Charge density of plate B, σ=−17.0×10−22C/m2

Electric field in regions can be found with the help of Gauss Law. In the regions, I and III, electric field E is zero. This is because charge is not enclosed by the Gaussian surfaces of the plates.

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

E=∈0σ

Where,

∈0= Permittivity of free space =8.854×10−12N−1C2m−2

∴E=8.854×10−1217.0×10−22

        =1.92×10−10N/C

Therefore, electric field between the plates is 1.92×10−10N/C.