74.
$\theta$
L
m
m
d
Students use a pith ball electroscope, shown in the figure, consisting of two identical and equally charged pith balls
of mass m hanging from strings of equal length L and negligible mass. The pith balls are a distance d apart, and the
strings make an angle $\theta$. Measuring which of the following quantities will provide sufficient and necessary data to
determine the net charge on each pith ball?
(A) $\theta$ and m
(B) $\theta$ and L
(C) L, d, and m
(D) $\theta$, L, and d