Electric Field Intensity Due To A Point Charge

Suppose we have to calculate electric field intensity at any point P due to a point charge q at O, where OP= r.

Consider a small positive test charge q0> at P.

According to Coulomb’s law, force at P is

F = 1/4Пε_o qq0/r² a_r

where a_r is unit vector directed from q towards q0.

As                    E = F/q0

Therefore by putting value of F in above equation, we get

E =       1/4Пε_o q/r² a_r

This is the expression for electric field intensity due to a point charge.

Note: Try to make the diagram for this problem yourself. If you are able to understand this article, then you can answer the following questions:

1. What is the force due to a point charge?

2. What is the electric field intensity due to a point charge?

Reference: This article is referred from my authored book “concepts of electromagnetic field theory” having ISBN 978-81-272-5245-8. In case of any doubt in this article or any other EMFT or physics related article, kindly post in the comment section.