Two real capacitors of equal capacitance (C1 = C2) are shown in the figure. Initially, while the switch S is open, one of the capacitors is uncharged and the other carries charge Q0. The energy stored in the charged capacitor is U0. Sometime after the switch is closed, the capacitors C1 and C2 carry charges Q1 and Q2, respectively; the voltages across the capacitors are V1 and V2; and the energies stored in the capacitors are U1 and U2.Which of the following statements is INCORRECT?
A. Q0 = ½ (Q1 + Q2)
B. Q1 = Q2
C. V1 = V2
D. U1 = U2
E. U0 = U1 + U2
(GR9677 #25)
Initial charge: Q0
Charge is conserved and distribute evenly
Q0 = ½ (Q1 + Q2)
(A) CORRECT
C = Q/V
For parallel capacitor V = V1 = V2
Given C1 = C2 → Q1 = Q2
(B) and (C) CORRECT
U = ½QV
V1 = V2 and Q1 = Q2
→ U1 = U2
(D) CORRECT
U = ½QV → Q = 2U/V
From (A) Q0 = ½ (Q1 + Q2),
2U0/V0 = ½ (2U1/V1 + 2U2/V2)
V0 = V1 = V2 → 2U0 = U1 + U2
(E) INCORRECT
Answer: E
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