試題詳解

51. A certain capacitor has a capacitance of 5 μF. After it is charged to 5 μC and isolated, the plates are brought closer together so its capacitance becomes 10 μF. The work done by the agent is about ______.
(A) −1.25 × 10^–6J
(B) 8.3 × 10^–7J
(C) −8.3 × 10^–7J
(D) 1.25 × 10^–6J
(E) −3.75 × 10^–6J