Question

Two equal point charges of +3.1x 10-6 C are placed 0.190 m apart. What are the magnitude and direction of the force each charge exerts on the other?

Answer 1

Since both charges are of equal signs, the force acts to repel them. The magnitude of this force is

$$F=\frac{1}{4\pi\epsilon_0}\frac{q\cdot q}{r^2}=\\\space\\ =\frac{1}{4\pi8.85\cdot10^{-12}}\cdot\frac{3.1\cdot10^{-6}\cdot3.1\cdot10^{-6}}{0.190^2}=\\\space\\ =2.39\text{ N}.$$