Why is the Charge on the Equivalent Capacitor the Same as C1?

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SUMMARY

The discussion centers on the relationship between charge and equivalent capacitance in a series circuit involving capacitors C1 and C2. When connected in series, the charge on the equivalent capacitor is equal to the charge on capacitor C1, which can be expressed as q1 = C1 * V1, where V1 is the voltage across C1. The formula for the equivalent capacitance is given by 1/Ceq = 1/C1 + 1/C2, confirming that the charge remains consistent across the series configuration.

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Homework Statement


Q17. Capacitors C1 and C2 are connected in series and a potential difference is applied to the combination. If the capacitor that is equivalent to the combination has the same potential difference, then the charge on the equivalent capacitor is the same as:

A. the charge on C1


Homework Equations



q = CV
1/Ceq = sum ( 1/Ci )

The Attempt at a Solution



Well the answer is given, but I don't understand it. I keep doing the problem according to the formulas, but I get q1*q2 / q1+q2
 
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No, that does not look right. I think the place where you are going wrong is maybe you are thinking that q_1=C_1 V. (This is not true because C1 does not have the full battery voltage V across it--part of it is across C1 and part across C2.) What is true is that q_1 = C_1 V_1.

So what is the charge on the equivalent capacitance in terms of C1,C2, and V?

Once you have that, you can find the charge on C1 by itself.
 

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