Capacitors reconnected (finding charge and potential)

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SUMMARY

The discussion centers on the behavior of capacitors when charges are redistributed. The key equation involved is Q = CV, where Q represents charge, C is capacitance, and V is voltage. Participants clarify that while the initial configuration appears to have a net charge of zero due to opposing charges on two conductors, the unequal sizes of charges Q1 and Q2 result in a net charge remaining, denoted as q. This understanding resolves the confusion regarding the net positive and negative charges on the conductors in the final configuration.

PREREQUISITES
  • Understanding of capacitor fundamentals, including charge and voltage relationships.
  • Familiarity with the equation Q = CV and its components.
  • Basic knowledge of electric charge behavior in conductors.
  • Concept of charge cancellation and net charge in electrostatics.
NEXT STEPS
  • Study the principles of charge distribution in capacitors.
  • Learn about the effects of unequal charge sizes on net charge calculations.
  • Explore advanced capacitor configurations and their applications in circuits.
  • Investigate the role of capacitance in energy storage and transfer.
USEFUL FOR

Students studying electrical engineering, physics enthusiasts, and anyone seeking to deepen their understanding of capacitor behavior and charge dynamics.

luigidorf
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Homework Statement


L4hGJ.jpg


Homework Equations


Q = CV

The Attempt at a Solution


It's already solved for me; I just don't understand it.

In figure (b) it looks like there are two separate conductors: one on top, and one on the bottom. The top piece has +Q on the left side and -Q on the right, and the bottom piece has the same thing except reversed. Seems to me that this would make the net charge on each conductor 0... But somehow they get to figure (c) where the top piece has a net positive charge and the bottom piece has a net negative charge. What am I missing?
 
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luigidorf said:
In figure (b) it looks like there are two separate conductors: one on top, and one on the bottom. The top piece has +Q on the left side and -Q on the right, and the bottom piece has the same thing except reversed. Seems to me that this would make the net charge on each conductor 0... But somehow they get to figure (c) where the top piece has a net positive charge and the bottom piece has a net negative charge. What am I missing?

The charges Q1 and Q2 are of different sizes. They don't completely cancel. They leave charge q remaining uncancelled.
 
Ah there it is. Thanks!
 

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