Calculating Capacitor Charge and Potential Difference in Series

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Homework Help Overview

The discussion revolves around calculating the charge and potential difference across capacitors connected in series. The original poster presents a scenario involving two capacitors, one charged and the other uncharged, and seeks clarification on the manipulation of the capacitor charge-voltage relationship.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants explore the relationship between charge and voltage in capacitors, questioning how to derive specific formulas from the fundamental equation Q = CV. There is a discussion on the implications of connecting capacitors in series versus parallel.

Discussion Status

Some participants have offered insights into the behavior of charge and voltage in the circuit, noting that the total charge remains constant and that the voltage across the capacitors must be equal in certain configurations. However, there is no explicit consensus on the application of these concepts to the original poster's questions.

Contextual Notes

There is an indication of confusion regarding the application of formulas and the configuration of the capacitors, with participants questioning the assumptions about series and parallel connections.

Soaring Crane
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A capacitor C1 carries a charge Q0. Is is then connected directly to a second, uncharged, capacitor C2.

What charge will each carry now? Q1 = Q0C1/(C1 + C2); Q2 = Q0C2/(C1 + C2)


What will be the potential difference across each?
V = Q0 / (C1 + C2)

-------||-------||--------
|*****C1*****C2******|
|********************|
|********************|
|********************|
|_______________________|

I know that the formula Q = CV is used, but how do you manipulate it (other than V = Q/C) to get the answers in bold?

Thanks.
 
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The voltage around the loop will be 0 in equilibrium, and whatever charge the second capacitor gets, the first one must lose. Does that help at all?
 
Soaring Crane said:
I know that the formula Q = CV is used, but how do you manipulate it (other than V = Q/C) to get the answers in bold?
Since the capacitors are connected in parallel, they have the same voltage (V). So the charges on the capacitors are: [itex]Q_1 = C_1V[/itex] and [itex]Q_2 = C_2V[/itex]. The total charge remains the same, so [itex]Q_0 = Q_1 + Q_2[/itex]. Solve for V.
 
I think I understand what you're saying, but I don't know how to apply it to the questions.
 
Oh, OK. Let me try it.
 

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