## Physics: Principles with Applications (7th Edition)

Use Coulomb’s law to calculate the magnitude of the force. $$F=k\frac{Q_1Q_2}{r^2}$$ $$=(8.99\times10^9\frac{N\cdot m^2}{C^2})\frac{(1.60\times10^{-19}C)^2}{(4.0\times10^{-15}m)^2}$$ $$=14N$$