Question

Two point charges are seperated by a distance of 100cm. With a magnitude of -10^-6 for both charges. Find the electric force between them

Answer 1

According to the Coulomb's law the force is:

$$F = k\dfrac{|q_1q_2|}{r^2 }$$

where $k=9\times 10^9 N\cdot m^2/C^2$ is the Coulomb's constant, $q_1=q_2=-10^{-6}C$ are the magnitude of the charges, and $r= 100cm = 1m$ is the distance between them. Thus, obtain:

$$F =9\times 10^9\cdot \dfrac{(-10^{-6})^2}{1^2 } = 9\times 10^{-3}N$$

Answer. $9\times 10^{-3}N$.