Question about charged capacitors and inserting a dielectric into one

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Homework Help Overview

The discussion revolves around the behavior of charged capacitors when a dielectric is inserted into one of them, particularly focusing on the changes in potential difference and charge distribution after disconnecting from a battery.

Discussion Character

  • Conceptual clarification, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants explore the initial charging of capacitors and the effects of inserting a dielectric. Questions arise about the conditions under which charge transfer occurs between the capacitors and the criteria for when this transfer ceases.

Discussion Status

Participants are actively questioning the mechanics of charge provision between the capacitors and discussing the conservation principles involved. There is a recognition of the need to establish equations to analyze the situation further, indicating a productive direction in the discussion.

Contextual Notes

Assumptions about the initial conditions of the capacitors and the effects of the dielectric are being examined, with a focus on the implications of removing the battery and the resulting charge dynamics.

Kaushik
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Homework Statement
The parallel combination of two air filled parallel plate capacitors of capacitance ##C## and ##nC## is connected to a battery of voltage, ##V##. When the capacitors are fully charged, the battery is removed and after that a dielectric material of dielectric constant ##K## is placed between the two plates of the first capacitor. The new potential difference of the combined system is?
Relevant Equations
##Q = CV##
##C_{eq}= C_1 + C_2## for parallel
## \frac{1}{C_{eq}}= \frac{1}{C_1} + \frac{1}{C_2}## for series
First when it is connected to the battery, the capacitors start accumulating charges such that the potential difference equals that of the battery. Then the current stops flowing.
##Q_1 = CV##
##Q_2 = nCV##
Where 1 and 2 represent the capacitor with capacitance C and nC respectively

Then, when we remove the battery and add a dielectric between the capacitor of capacitance ##C## (##C_{new} = KC##), the potential difference across it reduces. Now, the capacitor 2 starts behaving like a battery, providing charge to the capacitor 1.
After this, how can I proceed?
 
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Kaushik said:
providing charge to the capacitor 1
And when does this 'provision' come to an end ?
 
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BvU said:
And when does this 'provision' come to an end ?
When the potential difference between capacitor 1 and capacitor 2 become equal?
 
Correct.
And what is conserved during this provision process ?
Set up a set of equations before and after to find the new ##V##.
 
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