Parllel Plate Capacitors Connected Opposite

  • Thread starter Thread starter Fizzicist
  • Start date Start date
  • Tags Tags
    Capacitors Plate
Click For Summary

Homework Help Overview

The problem involves two capacitors connected in parallel to a voltage source, then disconnected and reconnected with opposite plates together. The original poster seeks to determine the decrease in energy of the system after this reconnection.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • The original poster attempts to calculate the initial charge on the capacitors and questions whether a new potential difference needs to be recalculated after reconnection. Other participants suggest finding the new charge and energy stored after the reconnection.

Discussion Status

The discussion is ongoing, with participants expressing uncertainty about the next steps. Some guidance has been offered regarding the relationship between charge and energy in the context of series connections, but no consensus has been reached on the approach to take.

Contextual Notes

Participants are navigating the implications of disconnecting and reconnecting capacitors, which raises questions about charge conservation and energy calculations. There is a lack of clarity on how to handle the new configuration and its effects on potential difference and energy.

Fizzicist
Messages
53
Reaction score
0

Homework Statement



Two capacitors are connected parallel to each other and connected to the battery with voltage 30 V. Let C1 = 9.8 micro F,C2 = 4.0 micro F be their capacitances. Suppose the charged capacitors are disconnected from the source and from each other, and then reconnected to each other with plates of opposite sign together.By how much does the energy of the system decrease?

Homework Equations



U = (1/2)QVFor PPC connected in parallel,

Q1 = C1V and Q2 = C2V

Ceq = C1 + C2 + C3...

The Attempt at a Solution



I found the charge stored on the plates initially, and was trying to find the charge stored on them after they were reconnect, but failed. I really don't know what to do. Do I have to find the new voltage too?
 
Physics news on Phys.org


If someone could just tell me if I have to recalculate a new potential difference, that would be great. I really have no clue how to proceed from here.
 
Can anyone help me with this? It's very frustrating, and I'm not quite sure how to approach it.
 
Note that when you connect the capacitors in series, they have the same charge on each other. So now you have to find the new charge on both of them and add up the stored energy in both.
 
  • Like
Likes   Reactions: yeshuamo

Similar threads

Two-layer dielectric, four-capacitor model vs three-capacitor model
  • · Replies 5 ·
Replies
5
Views
1K
What will be the final voltage across the 2 micro-farad capacitor?
  • · Replies 26 ·
Replies
26
Views
3K
Capacitors charged in parallel
  • · Replies 3 ·
Replies
3
Views
2K
Uncharged capacitors connected in series
  • · Replies 18 ·
Replies
18
Views
3K
Parallel combination of capacitors
  • · Replies 1 ·
Replies
1
Views
2K
Connecting two charged capacitors
  • · Replies 3 ·
Replies
3
Views
3K
Find the unknown capacity of two capacitors
  • · Replies 5 ·
Replies
5
Views
2K
Charge on plates in Millikan's Experiment
  • · Replies 5 ·
Replies
5
Views
2K
Find Charges on Capacitor w/ Floating Plates
  • · Replies 8 ·
Replies
8
Views
2K
Parallel Capacitors connected to Battery then D/C
  • · Replies 7 ·
Replies
7
Views
3K