(1) Two conducting hollow balls of diameter 3.75 cm are both initially charged by a bias voltage of +5000 V. When they are brought to a center-to-center distance of 10.0 cm, what is the electrostatic force between them?
(2) For the torsion balance, write the relationship between the exerted force and the angle of rotation.
(3) For the two conducting balls as described in problem 1, when one ball is attached to a torsion balance the wire is twisted by a torsional angle of 1°. Assuming the length of the lever arm as 10.0 cm, find the torsion constant of the wire. Show the calculation.