Capacitor how the plates are connected

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    Capacitor Plates
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Homework Help Overview

The discussion revolves around a problem involving two capacitors, C1 and C2, with given potential differences and the effects of connecting their plates. The subject area is primarily focused on capacitor behavior and charge conservation principles.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the initial charge calculations for each capacitor and express uncertainty about the configuration after connecting the plates. Questions arise regarding whether the capacitors are in series or parallel and how charge conservation applies in this context.

Discussion Status

Some participants have provided insights into the configuration of the capacitors and the concept of charge cancellation. However, there remains a lack of clarity for others regarding the application of these principles and the specific calculations needed to progress.

Contextual Notes

Participants note the challenge of understanding the implications of connecting the plates, particularly in relation to the final potential difference and the conservation of charge. There is a sense of frustration over the complexity of the problem despite its seemingly straightforward nature.

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Homework Statement


Capacitor C1 is charged so that potential difference between its plates is 20V. Another capacitor C2=33 microF has potential difference of 4 V. After plates of the capacitor that carry the charge of the opposite sign were connected the potential difference became 2V, find C1.


Homework Equations


Q=C/V


The Attempt at a Solution


I know Q1=C1*20V and Q2=(33uF)*(4V), but don't have the slightest clue what happens when the plates are connected. Are they connected in series, or parallel, does that even matter? I know there is a conservation of charges, but would it be something like (Q1-Q2) = Ceq*V? Thanks for any help or guidance
 
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They end up in parallel, and yes, there will be some charge cancellation.
 


I am sorry, but I still don't see what to do. I feel like this is a simple problem, but I am lost. I don't want to seem like I am just asking for an answer, but I've been struggling with this for the past 2 hours and nothing is making sense. After they are connected it would be something like Q=(C1+C2)*V, but what is the charge? Would Q= Q1-Q2 or something like that?
 


Yes, Q1 - Q2, or Q2 - Q1, whichever yields a positive remainder -- it is stated that the final potential difference is 2V, a positive number.
 

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