Finging the charge on each capacitor in series

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Homework Help Overview

The discussion revolves around finding the charge on two capacitors connected in series within a circuit that includes resistors and an emf source. The participants are considering the implications of the circuit being in a steady state after the switch has been closed for a long time.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants are exploring the relationship between the charges on the capacitors and the potential across each. There is mention of using equations related to capacitance and the loop rule to find the charges, as well as questioning how the charges on series capacitors are related.

Discussion Status

Some participants have provided guidance on the relationship between the charges on capacitors in series and have referenced external resources for further clarification. There is an ongoing exploration of the implications of the circuit being in a steady state, with some participants questioning the assumptions made about current flow and voltage drops across resistors.

Contextual Notes

Participants are working under the assumption that the switch has been closed for a long time, which implies that the capacitors are fully charged and no current is flowing in the circuit.

CogitoEAS
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Finding the charge on each capacitor in series

Homework Statement



In the circuit in the figure below, assume the resistance values are R1=1,400Ω and R2=2,500Ω, C1=55μF and C2=15μF, and the emf=5.5 V. The switch is labeled S.

Consider the circuit in the figure below and assume the switch has been closed for a very long time.

What are the charges on the two capacitors?

Screen Shot 2014-07-05 at 11.41.28 PM.png


Homework Equations



C=Q/V, Loop Rule - 5.5-(Q1/55e-6)-(Q2/15e-6)=0, 1/Ceq=(1/C1)+(1/C2)

The Attempt at a Solution



I think I'm just blanking on something here because it's either a matter of finding the potential across each capacitor or finding another equation relating Q1 and Q2 so that I can solve for both. Maybe Qtotal=CV(1-e^(-t/tau))=Q1+Q2?
 
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CogitoEAS said:

Homework Statement



In the circuit in the figure below, assume the resistance values are R1=1,400Ω and R2=2,500Ω, C1=55μF and C2=15μF, and the emf=5.5 V. The switch is labeled S.

Consider the circuit in the figure below and assume the switch has been closed for a very long time.



Homework Equations



C=Q/V, Loop Rule - 5.5-(Q1/55e-6)-(Q2/15e-6)=0, 1/Ceq=(1/C1)+(1/C2)

The Attempt at a Solution



I think I'm just blanking on something here because it's either a matter of finding the potential across each capacitor or finding another equation relating Q1 and Q2 so that I can solve for both. Maybe Qtotal=CV(1-e^(-t/tau))=Q1+Q2?

What is the question?

How are the charges on series capacitors related?

ehild
 
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Yes, sorry, I've added the central question "What are the charges on the two capacitors?" to the original post. I'm also 100% sure I spelled FINDING right in the title but for some reason the d keeps getting changed to a g?!
 
Thank you!
 
And we hen they say it has been switched on for a very long time they are hoping you will reason out 'the capacitors are as charged as they ever will be, so no current isnflowingr, now the voltage drop across resistors when there is no current is...'
 

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