A ping-pong ball of mass 3.0 x 10-4 kg is hanging from a light thread 1.0 m long, between two vertical parallel plates 10 cm apart, as shown. When the potential difference across the plates is 420 V, the ball comes to equilibrium 1.0 cm to one side of its original position. (a) What is the electric field intensity between the plates? (b) What is the tension in the thread? (c) What is the magnitude of the electric force deflecting the ball? (d) What is the charge on the ball?

see attached image