A ping-pong ball of mass 3.75 x 10-4 kg is hanging from a light thread 1.35 m long, between two vertical parallel plates 10cm apart, as shown. When the potential difference across the plate is 120V, the ball comes to equilibrium 1.35 cm to one side of its original position.

a) What is the electrical field intensity between the plates?

b) What is the Tension in the thread?

c) What is the magnitude of the electrical force deflecting the ball?

d) What is the charge on the ball?

e) What do you mean by conservation of charge?