Capacitor Question Homework: Finding the Potential Difference

  • Thread starter Thread starter Snazzy
  • Start date Start date
  • Tags Tags
    Capacitor
Click For Summary

Discussion Overview

The discussion revolves around a homework problem involving a capacitor in a circuit with resistors. Participants explore the implications of a switch being closed for an extended period, the behavior of current in the circuit, and the potential difference across the capacitor and resistors.

Discussion Character

  • Homework-related
  • Conceptual clarification
  • Technical explanation

Main Points Raised

  • One participant calculates the equivalent resistance and current, noting that the current splits across branches, but questions the potential difference across the capacitor using Kirchhoff's loop law.
  • Another participant explains that with the switch closed for a long time, the circuit reaches a static state where the capacitor behaves like an open circuit, resulting in no current flowing through it.
  • A follow-up question arises about whether current also does not flow through a 10 Ohm resistor, which is confirmed by another participant.
  • Participants discuss the implications of the second branch of the circuit not affecting the overall current, leading to a calculation of current and voltage differences across the resistors and capacitor.
  • A question is raised about the purpose of the 10 Ohm resistor, with one participant suggesting it affects the charge rate when the switch is closed.

Areas of Agreement / Disagreement

Participants generally agree on the behavior of the capacitor and the implications of the switch being closed, but there are questions regarding the role of the 10 Ohm resistor and its effect on the circuit, indicating some uncertainty.

Contextual Notes

There are assumptions regarding the static state of the circuit and the role of the resistors that may not be fully explored. The discussion does not resolve the purpose of the 10 Ohm resistor.

Snazzy
Messages
470
Reaction score
0

Homework Statement


2mhwndg.jpg




Homework Equations


V = IR
CV = Q



The Attempt at a Solution


I found the equivalent resistance to be 68 Ohms, then I found the current, then I found that the current splits 4/5 of its total across the branch with the capacitor, but if I apply Kirchhoff's loop law, I just get that the capacitor has a potential difference of 0 V.
 
Physics news on Phys.org
"The switch has been closed for a long time."

I don't know how this should be apparent an introductory level but...

With the switch closed for a while, everything is static, the currents are done changing because the capacitor has as much charged as it's going to get. So...

No current flows through the capacitor. It's, like, an open circuit.
 
Oh...so then no current also flows through the 10 Ohm resistor?
 
You've got it. well done
 
Okay, so if the 2nd branch doesn't affect the circuit, the current is 100 / (60+40) = 1A, and so the voltage difference across the 40 Ohm resistor is equal to the voltage difference across the capacitor? :S
 
Snazzy said:
Okay, so if the 2nd branch doesn't affect the circuit, the current is 100 / (60+40) = 1A, and so the voltage difference across the 40 Ohm resistor is equal to the voltage difference across the capacitor? :S

That's correct.
 
What's the point of that 10 Ohm resistor then?
 
I dunno. It would effect the charge rate when the switch is closed. Ask your prof.
 

Similar threads

  • · Replies 11 ·
Replies
11
Views
8K
  • · Replies 5 ·
Replies
5
Views
4K
Replies
2
Views
2K
  • · Replies 13 ·
Replies
13
Views
4K
  • · Replies 9 ·
Replies
9
Views
6K
  • · Replies 21 ·
Replies
21
Views
5K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 27 ·
Replies
27
Views
2K
  • · Replies 20 ·
Replies
20
Views
8K
  • · Replies 7 ·
Replies
7
Views
2K