Calculating Charge on Capacitors in Series

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Homework Help Overview

The discussion revolves around a circuit with two capacitors of 0.40 µF and 0.50 µF connected in series to a 9V battery. Participants are exploring the charge distribution on the capacitors and the relationship between charge, capacitance, and voltage in series circuits.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants are questioning the charge on each capacitor, specifically whether the total charge of 1.8 mC is shared equally or if it varies between the two capacitors. There is also discussion about the need to calculate the equivalent capacitance and the voltages across each capacitor to clarify the charge distribution.

Discussion Status

Some participants have provided guidance on how to approach the problem by suggesting that the voltages across the capacitors must add up to the total voltage of 9V. There is an ongoing exploration of the implications of the charge being the same for capacitors in series, but no consensus has been reached regarding the specific charge values on each capacitor.

Contextual Notes

Participants are working under the assumption that the charge on capacitors in series is the same, while also grappling with the calculations needed to determine the voltage across each capacitor. There is mention of potential rounding errors affecting the understanding of the charge distribution.

slammer
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Homework Statement


A circuit composed of 2 capacitors of .40MF and .50MF are connected in series to a 9V battery. Calculate the charge on each

I just have a general question. I know that capacitors in series have the same charge.
I found Q to be 2MC and I was wondering if 1.8MC is the charge on both caps or is it .9MC charge on both caps.
 
Last edited:
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slammer said:

Homework Statement


A circuit composed of 2 capacitors of .40MF and .50MF are connected in series to a 9V battery. Calculate the charge on each

I just have a general question. I know that capacitors in parallel have the same charge.
I found Q to be 1.8MC and I was wondering if 1.8MC is the charge on both caps or is it .9MC charge on both caps.

Capacitors in parallel have the same voltage but not necessarily the same charge unless the capacitances are the same.

Q = v * C

As for your question about the 1.8 mC - that is what is across the "equivalent" capacitor.

If you were to figure the voltages of the 2 capacitors and know they are supposed to add to 9 v, you will be able to answer your own question about how the charges are distributed.
 
Oops sorry my bad i mean capacitors in series have same charge. But I can't solve for V w/o finding out the capacitance on each capacitor. So what I am trying to say is does the both of the capacitors get 1.8mC of charge or do they each get .9mC?
 
slammer said:
Oops sorry my bad i mean capacitors in series have same charge. But I can't solve for V w/o finding out the capacitance on each capacitor. So what I am trying to say is does the both of the capacitors get 1.8mC of charge or do they each get .9mC?

What voltage do you get across each capacitor for both of those possibilities?

Which possibility adds up to 9 v adding the voltages of both capacitors? Because that's the one that's your answer.

Btw, where did the 1.8 mC come from? Didn't you calculate the equivalent capacitance and multiply by the voltage?
 
Last edited:
LowlyPion said:
What voltage do you get across each capacitor for both of those possibilities?

Which possibility adds up to 9 v adding the voltages of both capacitors? Because that's the one that's your answer.

Btw, where did the 1.8 mC come from? Didn't you calculate the equivalent capacitance and multiply by the voltage?

round errors and I figured it out. 1.8mC gets dumped on both of the caps.
 
slammer said:
round errors and I figured it out. 1.8mC gets dumped on both of the caps.

Well if you had used 2 mC it would have maybe been a little more obvious?

Cheers.
 

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