CP Two identical spheres are each attached to silk threads of length \(L=0.500
\mathrm{m}\) and hung from a common point (Fig. P21.68). Each sphere has mass
\(m=8.00 \mathrm{g} .\) The radius of each sphere is very small compared to the
distance between the spheres, so they may be treated as point charges. One
sphere is given positive charge \(q_{1},\) and the other a different positive
charge \(q_{2} ;\) this causes the spheres to separate so that when the spheres
are in equilibrium, each thread makes an angle \(\theta=20.0^{\circ}\) with the
vertical. (a) Draw a free-body diagram for each sphere when in equilibrium,
and label all the forces that act on each sphere. (b) Determine the magnitude
of the electrostatic force that acts on each sphere, and determine the tension
in each thread. (c) Based on the information you have been given, what can you
say about the magnitudes of \(q_{1}\) and \(q_{2} ?\) Explain your answers. (d) A
small wire is now connected between the spheres, allowing charge to be
transferred from one sphere to the other until the two spheres have equal
charges; the wire is then removed. Each thread now makes an angle of
\(30.0^{\circ}\) with the vertical. Determine the original charges. (Hint: The
total charge on the pair of spheres is conserved.)