Calculating Current in Parallel Circuits for Scientists

Click For Summary

Homework Help Overview

The discussion revolves around calculating current in parallel circuits, specifically focusing on the application of Ohm's law (V=IR) and the current divider rule. Participants explore how to set up the problem and the implications of having multiple resistors in parallel.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the use of the current divider rule and its necessity in finding total current. Questions arise about the application of V=IR and how it relates to parallel circuits. There is also inquiry into the specifics of the current divider rule and its formula when dealing with multiple resistors.

Discussion Status

The discussion is active, with participants sharing insights about the current divider rule and its application in circuits with three branches. Some guidance has been provided regarding the relationship between total current and individual branch currents, although no consensus has been reached on the exact formulas to use.

Contextual Notes

Participants are navigating the complexities of parallel circuits and the formulas involved, indicating a need for clarity on how to approach problems with varying numbers of resistors. There is an implicit understanding that assumptions about voltage and resistance are critical to the discussion.

map7s
Messages
145
Reaction score
0
This is just a general question... when trying to solve for the current in each resistor in a parallel circuit, how do you go about setting it up? (I know that the equation V=IR comes in handy...)
 
Physics news on Phys.org
You could use the current divider rule. That would require you to find the total current in the circuit. Whats wrong with using V=IR?
 
What is the current divider rule?
 
Its used to find current when resistances are hooked up in parallel with each other. Here is a wiki picture that should clear things up for you:
http://upload.wikimedia.org/wikipedia/en/4/47/Cdr.GIF
 
Last edited by a moderator:
That really helped! But if the circuit has three branches in parallel, does the formula change to I1=Itotal x ((R2+R3)/(R1+R2+R3)) ?
 
It changes a little when we have more than two resistances. Let's consider a circuit with three parallel branches. We know that the voltage drop across any resistor in a parallel circuit is equal to that of the source:

[tex]I_x = \frac{V_s}{R_x}[/tex]

[tex]V_s = I_TR_T[/tex] <--the source voltage is equal to the total current times the total resistance.

Now substituting [itex]I_TR_T[/itex] for Vs in the first equation (Ix).

[tex]I_x = \frac{I_TR_T}{R_x}[/tex]

We can therefore conclude that the current through any parallel resistor is in fact:
[tex]I_x = \frac{R_T}{R_x}\cdot I_T[/tex]

Hope it helps/
 

Similar threads

How to determine if electrical components are connected in parallel or in series?
  • · Replies 10 ·
Replies
10
Views
2K
Finding the Current Through a Resistor (Working With Parallel and Series)
  • · Replies 3 ·
Replies
3
Views
2K
Electrical Circuits - Parallel vs. Series
  • · Replies 14 ·
Replies
14
Views
2K
Current through a circuit when the key is open
  • · Replies 42 ·
2
Replies
42
Views
6K
Calculation of current in driven series RLC circuit
  • · Replies 8 ·
Replies
8
Views
3K
Why do the headlights on the car become dim when the car is starting?
  • · Replies 4 ·
Replies
4
Views
2K
Circuits question, series vs parallel
  • · Replies 5 ·
Replies
5
Views
2K
Identical Batteries in Parallel do not Draw Same Current, Non-Ideal?
  • · Replies 7 ·
Replies
7
Views
1K
How Does Coil Configuration Affect Current in LR Circuits?
  • · Replies 14 ·
Replies
14
Views
5K
Worst-case power consumed by a circuit with MOSFETs
  • · Replies 2 ·
Replies
2
Views
1K