Exercises: Coulomb's Law

Newton's Law of Gravitation is $F = \frac{Gm_1 m_2}{r^2}$. Which term in this formula plays the same role as the charges in Coulomb's Law?

Two charges of the same sign are brought close together. What type of electric force acts between them?

Which feature do Coulomb's Law and Newton's Law of Gravitation share?

Two protons are separated by a distance $r$. Which of the following correctly describes the electric force between them?

Calculate the magnitude of the electric force between two charges: $q_1 = +3 \times 10^{-6}$ C and $q_2 = +5 \times 10^{-6}$ C, separated by $r = 0.30$ m. Express your answer in newtons to two significant figures.

Calculate the magnitude of the electric force between $q_1 = +2 \times 10^{-6}$ C and $q_2 = -4 \times 10^{-6}$ C separated by $r = 0.20$ m. Express your answer in newtons to two significant figures.

The electric force between two charges separated by distance $r$ is $F$. If the distance is doubled to $2r$ (charges unchanged), what is the new force?

Three charges are on a line. Charge A ($+4 \mu$C) is at position 0, charge B ($-2 \mu$C) is at 0.30 m, and charge C ($+3 \mu$C) is at 0.50 m. Find the net force on charge B.

Taking rightward as positive, what is the net force on B in newtons? (Positive = right, negative = left.) Express your answer to two significant figures.

In the same setup (A at 0, B at 0.30 m, C at 0.50 m), what is the net force on charge C? (Positive = right, negative = left.) Express your answer to two significant figures.