\begin{problem*}{23.50}
A small sphere of charge $q_1=0.800\U{$\mu$C}$ hangs from the end of a
-spring as in Figure P23.50a. When another small sphere of charge
+spring as in Figure~P23.50a. When another small sphere of charge
$q_2=-0.600\U{$\mu$C}$ is held beneath the first sphere as in Figure
P23.50b, the spring stretches by $d=3.50\U{cm}$ from its original
length and reaches a new equilibrium position with a separation