Two point charges and are placed apart in air

PHYSICS · Subjective · A Level · Physics · Fields and their consequences · Fields and their consequences

Problem

Two point charges

q_1 = 3\,\mu\text{C}

and

q_2 = 5\,\mu\text{C}

are placed

20\,\text{cm}

apart in air. Calculate the magnitude of the electrostatic force between them. (Give your answer in newton.)