Whenever a charge of magnitude q coulombs is placed in a vacuum field, it creates an Electric Field. It spreads all around the charge in every direction.
Formula for calculating Electric Field generated due to a Single Charge Q in vacuum is :
where Q is the amount of charge present, r is the displacement (vector) with respect to that charge to the point in space.
The force exerted on an another charge q present around it is given by :
Also the charge q is also generating an electric field around it due to which charge Q experiences an equal amount of force but in opposite direction.