Question

Electric field due to single point placed in the air

Answer 1

Electric Field is electrostatic force per unit point charge.
E=F/q
Consider a charge q
Electric Field due to charge = Kq/r²
k =1/4π£
£= 8.85×10^(-12)

Answer 2

electric field :- the force acting on a unit positive charge place at that point is known as electric field at that point .
let a point charge Q placed at r distance in air
then ,
E =kQ/r^2 acting on that point
we assume in air permitivity of medium just like permitivity of medium in vaccume so here no change in ' k'