Question

Two charged particles are placed 2.0 meters apart. The first charge is +2.0 E-6 C, and the second charge is +4.0 E-6 C. What is the electrical force between the two charges?
(k = 9.0 E9 Nm^2/c^2)
A. +1.8 E-2 N and it is repulsive
B. +3.6 E-2 N and it is repulsive
C. +4.5 E-2 N and it is attractive
D. +9.0 E -2 N and it is attractive

Answer 1

F = kq1q2/r^2 

q1 is first charge 
q2 is second charge 
k is 9 E9 
r is distance between them 

F = (9E9)(2 E-6)(4 E-6)/2^2 = 0.018 N 

A postive answer indicates a repulsive force