Answer
(a) $Q = 1.8\times 10^{-8}~C$
(b) $U = 1.35\times 10^{-6}~J$
Work Step by Step
(a) We can find the charge on the capacitor:
$Q = C~\Delta V$
$Q = (\frac{\epsilon_0~A}{d})~\Delta V$
$Q = (\frac{(8.854\times 10^{-12}~F/m)~(0.10~m)^2}{0.75\times 10^{-3}~m})~(150~V)$
$Q = 1.8\times 10^{-8}~C$
(b) We can find the energy stored in the capacitor:
$U = \frac{1}{2}~Q~V$
$U = \frac{1}{2}~(1.8\times 10^{-8}~C)(150~V)$
$U = 1.35\times 10^{-6}~J$
