11. In the following figure, we have V = 9.0 V, C₂ = 3.0 µF, and C₄ = 4.0 µF, and all the capacitors are initially uncharged. When switch S is closed, a total charge of 20 µC passes through point a and a total charge of 8.0 µC passes through point b. What is capacitance C₃ (uF)?

詳解 (共 1 筆)

助人為本

詳解 #7384054

2026/05/26

所以解這題的關鍵公式只有一個就是Q=C*V

所以第一步我們要先找出C3上的電荷Q3

所以根據電荷(流)守恆定律

Qa=Q3+Qb

20=Q3+8

所以Q3=12uC

接著算出並聯區段的電壓

由Q4和C4可以推算出電壓(又和3是並聯，所以電壓一樣)

8/4=2

所以就可以算出C3會等於12/2=6