Capacitors C 1=10 ? F and C 2=28 ? F are each charged to 25V , then disconnected

Question

Capacitors C1=10?F and C2=28?F are each charged to 25V , then disconnected from the battery without changing the charge on the capacitor plates. The two capacitors are then connected in parallel, with the positive plate of C1connected to the negative plate of C2 and vice versa.

Part A: Afterward, what is the charge on each capacitor?

Express your answer using two significant figures. Enter your answers numerically separated by a comma.

(Q1,Q2) __________?F

Part B: What is the potential difference across each capacitor?

Express your answer using two significant figures. Enter your answers numerically separated by a comma.

(?V1, ?V2) ___________ V

Answer attempted for Part A: (83.3,166.7), (212,331),(118,184),(250,700),(2x10^-6,7x10^-6)

Part B: (25,25)

Explanation / Answer

a)

Charge on each capccitor when connected to 12 Volts

Q1=C1V=10*25=250 uC

Q2=C2V =28*25=700 uC

Net charge when battery disconnected and connected in parallel

Q=700-250 =450 uC

Charge on each capacitor is

Q1=Q*(C1/C1+C2)=450*(10/10+28) =118.4 uC

Q2=Q*(C2/C1+C2)=450*(28/10+28)=331.6 uC

b)

Voltage acorss each capcitor is

V1=V2=Q/(C1+C2)=450/(10+28) =11.84 Volts

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