MY BIGGEST PROBLEM in capacitance

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    Capacitance
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Homework Help Overview

The discussion revolves around a problem involving three capacitors with capacitances of 8.4 F, 8.4 F, and 4.2 F, initially connected in series across a 36 V potential difference, and then reconnected in parallel without discharging. The main question is about determining the voltage across each capacitor in the parallel configuration.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the relationship between capacitance, charge, and voltage, questioning how to determine the capacitance in series versus parallel configurations. There is confusion regarding whether the total voltage remains the same when switching from series to parallel connections.

Discussion Status

Some participants have offered insights into the behavior of capacitors in series and parallel, noting that in series, each capacitor has the same charge, while in parallel, the total charge can be used to find the common voltage. However, there is still uncertainty regarding the calculations and relationships involved.

Contextual Notes

Participants are operating under the constraints of a homework assignment, which may limit the information they can use or the methods they can apply. There is an emphasis on understanding the principles rather than providing direct solutions.

meLzee
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Homework Statement




THREE CAPACITORS HAVING CAPACITANCE 8.4 F, 8.4 F, 4.2 F ARE CONNECTED IN SERIES ACROSS A 36 V POTENTIAL DIFFERENCE. THE CAPACITORS ARE DISCONNECTED FROM THE POTENTIAL DIFFERENCE WITHOUT ALLOWING THEM TO DISCHARGE. THEY ARE THEN RECONNECTED IN PARALLEL WITH EACH OTHER, WITH THE POSITIVELY CHARGED PLATES CONNECTED TOGETHER. WHAT IS THE VOLTAGE ACROSS EACH CAPACITOR IN PARALLEL COMBINATION?

PLEASE HELP ME WITH THIS. THANX.
 
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meLzee said:

Homework Statement




THREE CAPACITORS HAVING CAPACITANCE 8.4 F, 8.4 F, 4.2 F ARE CONNECTED IN SERIES ACROSS A 36 V POTENTIAL DIFFERENCE. THE CAPACITORS ARE DISCONNECTED FROM THE POTENTIAL DIFFERENCE WITHOUT ALLOWING THEM TO DISCHARGE. THEY ARE THEN RECONNECTED IN PARALLEL WITH EACH OTHER, WITH THE POSITIVELY CHARGED PLATES CONNECTED TOGETHER. WHAT IS THE VOLTAGE ACROSS EACH CAPACITOR IN PARALLEL COMBINATION?

PLEASE HELP ME WITH THIS. THANX.
What work have you done so far? Can you write the relationship between C, Q and V? How do you determine C for three capacitors in series? In parallel?

AM
 
C = Q/V

i got confused on how to solve their own voltages. i mean is the total voltage when they are connected in series. the same as when they are connected then in parallel?
 
When three capacitors are connect in series, what is the resultant capacitance of the combination? In the series combination, each capacitor has the same charge.
When they are connected in parallel, you know the total charge. You can find the resultant capacity of the parallel combination. From that you can find the common voltage.
 

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