A thin metal plate P is inserted between the plates of a parallel-plate capacitor having capacitance C such that its edges make contact with both plates, as shown in the figure. The new capacitance becomes

Step-by-step solution

When the thin metal plate P is inserted such that its edges make contact with both plates of the capacitor, it effectively short-circuits the two plates. Because the plates are connected by a conducting material, the potential difference V between them becomes zero for any finite charge. The capacitance of a capacitor is defined as C = Q V . Substituting V = 0 , the new capacitance becomes C' = Q 0 . Therefore, the new capacitance is infinite.