Two small balls with a mass of 1 g each are hanging on two separate strings 0.5 m (50 cm) long attached to a common point. They are given an identical negative charge and spread apart to a distance 4 cm from each other.

1. Determine the charge on each ball by finding the forces in equilibrium and using Coulomb's law.
2. How many excess electrons are there on each ball not cancelled by positive charge?
3. What will happen in an identical situation if the mass of the balls is cut in half?
4. What would happen if the charge on each ball is doubled?
5. What experiments might you do to determine the sign of the net charge on the balls?