Question

Coulomb's Law
A $7.50-nC$ point charge is located $1.80m$ from a $4.20-nC$ point charge.
(a) Find the magnitude of the electric force that one particle exerts on the other.
(b) Is the force attractive or repulsive?

Answer 1

(a) $|F|=\frac{k_e|q_1||q_2|}{r^2}$
$F=\frac{k_e{e}^2}{r^2}=\frac{(8.99\times {10}^{9}N.m^2/C^2)(7.50\times {10}^{-9}C)(4.20\times {10}^{-9}C)}{(1.80m{)}^2}$
$=8.74\times {10}^{-8}N$
(b) The charges are like charges.$\text{The force is repulsive.}$