Is this statement correct with the right reasoning?

  • Context: High School 
  • Thread starter Thread starter yeezyseason3
  • Start date Start date
  • Tags Tags
    capacitors circuit
Click For Summary

Discussion Overview

The discussion revolves around the behavior of a battery-bulb-capacitor circuit when the capacitor is replaced with one that has twice the area. Participants explore the implications of this change on the circuit's operation, particularly regarding the duration the bulb remains lit and the associated electrical principles.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant claims that increasing the capacitor's area leads to more charge accumulation, resulting in the bulb staying on longer due to a longer time for the charge to zero out the net electric field.
  • Another participant questions the validity of the claim that "current stays the same," suggesting that the current changes over time and that the time constant of the circuit is affected by the increased capacitance.
  • A different participant points out that the fringe field of a capacitor is more complex than described and that the formula provided may only apply under specific conditions, particularly far from the edges of the capacitor.
  • One participant emphasizes the need for a clear circuit diagram to ensure all participants understand the configuration being discussed, indicating that the term "simple circuit" requires further clarification.

Areas of Agreement / Disagreement

Participants express differing views on the behavior of the circuit, particularly regarding the current and the complexity of the fringe field. There is no consensus on the correctness of the initial claim or the implications of the capacitor's area change.

Contextual Notes

Limitations include the lack of a specific circuit diagram, which may lead to misunderstandings about the circuit's configuration and operation. Additionally, assumptions about the behavior of current and the applicability of the fringe field formula remain unresolved.

yeezyseason3
Messages
16
Reaction score
0
Assume you have a simple battery-bulb-capacitor circuit. If you replace the capacitor with one that has twice the area as the old capacitor, the bulb will stay on longer because there has to be more charge to accumulate on the plates of the capacitor to zero out the net electric field. Mathematically speaking in (Q/A)/2εo (equation of the fringe field of a capacitor) if A increases, Q has to also to get a net fringe equivalent to the electric field inside the wire. Since current stays the same and more charge has to accumulate, it takes longer.
 
Physics news on Phys.org
yeezyseason3 said:
Assume you have a simple battery-bulb-capacitor circuit.

depending on how it is wired, the bulb isn't likely to work
Do you understand what a capacitor is and how it works ?

show a circuit for your idea so we can confirm what you are talking about
Dave
 
yeezyseason3 said:
Since current stays the same and more charge has to accumulate, it takes longer.
I think what you wrote was generally good, but it is a little hard to claim "current stays the same" in a situation like this where the current changes over time. I would say instead that the time constant is RC, since C is double, then RC is also double, and everything takes twice as long.
 
Besides what was already said, the fringe field is not described by that simple formula, it is quite complicated and depends on position.
The formula may be OK for points very far from the edges of the capacitor, so exactly what the fringe field is not. :)
 
yeezyseason3 said:
Assume you have a simple battery-bulb-capacitor circuit.
A "simple" circuit still needs to be described - even when there are only three components. A diagram usually makes sure that everyone understands your question.
 
  • Like
Likes   Reactions: davenn

Similar threads

  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 7 ·
Replies
7
Views
2K
Replies
152
Views
8K
  • · Replies 4 ·
Replies
4
Views
3K
  • · Replies 103 ·
4
Replies
103
Views
9K
  • · Replies 7 ·
Replies
7
Views
3K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 3 ·
Replies
3
Views
6K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 101 ·
4
Replies
101
Views
10K