Which of the following is an example of the electromagnetic force?

Two point charges, $q_a$ and $q_b$, are separated by a distance $r$. What is the magnitude of the electric force on charge $q_a$ due to $q_b$ according to Coulomb's Law?

Which of the following best describes Coulomb’s Law for the electrostatic force between two point charges?

If the force between two charges is F when the distance is d, what will the force between the two charges be if they were moved to a distance of 2d?

In which direction will the −1 C charge move? If it has a mass of 10 g, what will its initial acceleration be?

What is the direction of the net force on the charge at the center of the square in the following figure?