What is the final charge and potential difference on each capacitor?

In summary, the conversation discusses a circuit with three capacitors and a voltage of 30V applied across two points. After one capacitor is fully charged, the switch is thrown and the final charges and potential differences on each capacitor are discussed. The conversation ends with confirmation that the calculation for the final charge on C1 is correct.
  • #1
ooohffff
74
1

Homework Statement


In the circuit shown in the figure, C1 = 1.0 µF, C2 = 1.9 µF, C3 = 2.8 µF, and a voltage Vab = 30 V is applied across points a and b. After C1 is fully charged the switch is thrown to the right. What is the final charge and potential difference on each capacitor?

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Homework Equations



Q=CV

The Attempt at a Solution



I found everything (V1, Q2, V2, Q3, V3) except for Q1. I tried doing Q1 = CeffV1, but the answer was wrong.
 
Last edited:
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  • #2
Ok so since V1=V2+V3, I did Q1/C1 = Q2/C2 + Q3/C3. Solving for Q1, I get Q1 = C1[ Q2/C2 + Q3/C3].

Q2=Q3=q

Q1=C1*q[1/C2 + 1/C3]

Plugging in the numbers, when q = 15.9μC, I get Q1 = 1.4*10-5 C. Does that look right?
 
Last edited:
  • #3
ooohffff said:
Plugging in the numbers, when q = 15.9μC, I get Q1 = 1.4*10-5 C. Does that look right?
That looks right for the final charge on C1, yes.
 
  • #4
gneill said:
That looks right for the final charge on C1, yes.
Thank you!
 

1. What is the final charge on a capacitor?

The final charge on a capacitor is the maximum amount of electric charge that the capacitor can hold. It is determined by the capacitance of the capacitor and the voltage applied to it.

2. How is the final charge on a capacitor calculated?

The final charge on a capacitor can be calculated using the formula Q = CV, where Q is the charge, C is the capacitance, and V is the voltage.

3. What factors affect the final charge on a capacitor?

The final charge on a capacitor is affected by the capacitance, voltage, and the initial charge on the capacitor. The type of dielectric material used in the capacitor can also affect the final charge.

4. How does the final charge on a capacitor relate to the energy stored in the capacitor?

The energy stored in a capacitor is directly proportional to the square of the final charge on the capacitor. This means that as the final charge on the capacitor increases, the energy stored in the capacitor also increases.

5. Can the final charge on a capacitor be greater than the initial charge?

Yes, the final charge on a capacitor can be greater than the initial charge if the voltage applied to the capacitor is higher than the initial voltage. However, this increase in charge is limited by the capacitance of the capacitor.

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