FIGURE 2 31
Solution
(a) The charge on the capacitor is
      Q = CV = 900 × 10–12 F × 100 V = 9 × 10–8 C
The energy stored by the capacitor is
      = (1/2) CV 2 = (1/2) QV
= (1/2) × 9 × 10–8C × 100 V = 4 5 × 10–6 J
(b) In the steady situation, the two capacitors have their positive
plates at the same potential, and their negative plates at the
same potential Let the common potential difference be V¢