The electric field intensity due to a point charge

Consider a positive charge +q due to which the intensity of the electric field at a point P is to be calculated.

To find the intensity of electric field at point P, consider the positive test charge qₒ situated at that point.

Therefore,

Electric force on positive test charge qₒ

F = [1/4π€₀].[q.q₀/r²] Newton

Electric field intensity at a point P,

E=F/qₒ

F = E.qₒ

E.qₒ = [1/4π€₀].[q.q₀/r²]

E = [1/4π€₀].[q/r²] N/C