How do Resistors and Capacitors behave in parallel circuits?

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Discussion Overview

The discussion revolves around the behavior of resistors and capacitors in parallel circuits, focusing on current flow, circuit analysis, and conceptual understanding of these components in various configurations. Participants explore theoretical scenarios and practical implications without reaching definitive conclusions.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • Some participants express confusion about current flow in circuits with resistors and capacitors in parallel, particularly regarding the idea of current taking the path of least resistance.
  • One participant suggests that current through the resistor is independent of the current through the capacitor, depending only on resistance and battery values.
  • Another participant challenges the notion of current only traveling through the path of least resistance, stating that current flows through all paths and that circuit analysis aims to quantify this flow.
  • It is noted that in practical scenarios, a resistor in parallel with a capacitor allows for independent current paths, and the behavior of each component can be analyzed separately.
  • Concerns are raised about the idealization of circuits, with one participant arguing that real circuits have inherent resistance and inductance, complicating the analysis.
  • Some participants emphasize the importance of practical experimentation, suggesting that using ammeters in a circuit can provide insights into the behavior of current through resistors and capacitors.
  • There is mention of the capacitor drawing infinite current when connected to a battery, raising questions about the implications of such scenarios.

Areas of Agreement / Disagreement

Participants do not reach consensus on the behavior of current in parallel circuits involving resistors and capacitors. Multiple competing views are presented, particularly regarding the interpretation of current flow and the implications of ideal versus real circuit conditions.

Contextual Notes

Limitations include assumptions about ideal circuit conditions, the neglect of resistance in wires and components, and the complexity introduced by real-world factors such as inductance and resistance.

lollol
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I get very confused when you have circuits involving Capacitors and Resistors

Especially the concept of current traveling through the path of least resistance

1) Let's say you have a circuit with a battery... with a resistor in parallel first, then a capacitor in parallel to the resistor.. does the current NOT pass thru the resistor at all.. since the capacitor route has no resistance?

I've included an image called CIRCUIT 1

2) Let's say you have the following scenario in CIRCUIT 2... diagram is provided... what happens when you close the switch?? does all of it pass into the capacitor ? or if it splits, how does it split :(

Is there a simple conceptual way to understand these rules so that I don't have to keep memorizing what happens with diff. scenarios
 

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lollol said:
I get very confused when you have circuits involving Capacitors and Resistors

Especially the concept of current traveling through the path of least resistance

1) Let's say you have a circuit with a battery... with a resistor in parallel first, then a capacitor in parallel to the resistor.. does the current NOT pass thru the resistor at all.. since the capacitor route has no resistance?

Well, the images are waiting for approval, yet, but I can say the current through the resistance is independent of the current through the capacitor, since it depends only on the resistance and battery values.
 
lollol said:
Especially the concept of current traveling through the path of least resistance
This phrase has little value in circuit analysis. Current always travels through all paths, not just the path of least resistance. The goal of circuit analysis is to determine exactly how much current goes through each path.
 
If you go ahead and actually hook up such a circuit and put ammeters in each branch, you'll see the resistor current go to a stable value almost immediately and then stay there. You'll see the capacitor current go to a peak value and then fall slowly toward zero (if you use a good digital meter, you'll be able to see how it approaches zero and that's interesting).
 
Those circuits don't exist. You can't made such a circuit. The wires, the battery and the capacitor have resistance and inductance.
You can analyze what happens if you connect real batterys to real capacitors but you must take into account the resistance, that is not 0.

In fig.1 a capacitor that is connected to a battery ( you didnt draw the switch, but I suppose there is a switch ) draws infinite intensity.

In fig.2 there is a short-circuit -> infinite intensity.
 
I'm just confused as to what happens in a situation where a resistor is in parallel with a capacitor

The only scenario I can understand so far is: what happens when a resistor is in series with a capacitor. That's it.
 
lollol said:
I'm just confused as to what happens in a situation where a resistor is in parallel with a capacitor

The only scenario I can understand so far is: what happens when a resistor is in series with a capacitor. That's it.

The thing you need to always remember is that parallel circuits are essentially independent. (I am speaking here of voltage circuits). In a manner of speaking, the computer I am writing this on is possibly in parallel with the radio you might be listening to right now. So, the current through the parallel resistor is independent of the current into the parallel capacitor, etc. So, this allows you to look at parallel circuit branches as though they were little isolated circuits, provided you can figure out the voltage for that branch (usually the same in simple circuits). If you possibly can take a lab course in this, do so. It helps immensely to actually see this stuff.

Anyway, the most important thing a resistor in parallel with a capacitor does is drain off the capacitor charge after the switch is opened. Keeps you from getting a shocking experience.
 

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