Solving Current Divider Rule with 30V Voltage Source

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Discussion Overview

The discussion revolves around solving a circuit problem involving a 30V voltage source and determining the current through a 20 Ohm resistor using the current divider rule. The context includes concepts from electrical engineering, specifically focusing on circuit analysis and current division.

Discussion Character

  • Homework-related
  • Technical explanation
  • Exploratory

Main Points Raised

  • Amit describes a circuit problem involving a 30V source and a 20 Ohm resistor, initially calculating a total equivalent current of 2A flowing through a 5 Ohm resistor.
  • Amit's assumption leads to a division of current that he calculates as 2/3A, which he later realizes is incorrect, as the actual current is 0.5A.
  • A participant confirms that 2A flows from the source through the 5 Ohm resistor and explains that the current divides equally due to equal resistance in both branches, resulting in 1A through each path.
  • The participant notes that the direction of current does not affect the calculation, and a negative sign in results indicates an incorrect initial assumption about current direction.
  • Amit acknowledges the importance of considering total resistance in circuit problems rather than focusing on individual resistors.

Areas of Agreement / Disagreement

Participants generally agree on the method of calculating current through the circuit, but there is no explicit consensus on the initial assumptions or the approach taken by Amit. The discussion reflects a learning process rather than a resolved issue.

Contextual Notes

Amit's initial misunderstanding of current division and resistance interactions highlights the complexity of circuit analysis, particularly for those new to the concepts. The discussion does not resolve all uncertainties regarding the application of the current divider rule.

Who May Find This Useful

This discussion may be useful for students studying electrical engineering, particularly those grappling with circuit analysis and the current divider rule.

amitjakob
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Hello everyone.
im amit, newbie in this forums, hopefully I am posting my question in the correct one.
anyways, i was trying to solve this qustion from last semester considering the attached image as a circut
with voltage source of 30V

the task was to find the current over the resistor position diagonally R=20 Ohm

My assumption was with a total equivalent current of 2A is flowing over the 5 Ohm resistor , then to be divided between 10/20 Ohm resistors and then again between 10/20 ... what gives to result of 2/3A which is ... wrong.

result is 0.5A , but why ? does it matter in which direction i consider the current flow ? how can I know which is the right direction if so ?

thanks a lot, exam coming by the end of the week
cya around. amit.
 

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You are correct with that 2A flows from the source through the 5 Ohm resistor. Now look at the equivalent resistance on both branches. Both paths have a 20 Ohm resistance (20 Ohm on left and 20||20 + 10 = 20 Ohm). So the current is divided equally to 1A each. So now that 1A flows through the 10 Ohm resistor and gets to the point where the diagonal 20 Ohm connects with the vertical 20 Ohm. Both paths have equal resistance so the current evenly splits again to 0.5A each.

The direction does not matter. In general when you solve for current and get a minus sign that just means your initial guess at the direction was wrong. The current flows the opposite way instead.
 
Allllright .. i think i got it now

from what i got from your answer one should always consider the total resistance when one calculate those sorts of problem, i tried to guess it each time with a specific resistor with a specific resistance and didnt consider other resistors might be connected and influencive.

now i know

Thanks:biggrin:

Amit, Germany.
 
Hope it helps. This stuff becomes easier as you get more experience doing these types of problems.
 
Corneo said:
Hope it helps. This stuff becomes easier as you get more experience doing these types of problems.

Thanks man, hopefully i can just forget about it after this friday, if ill pass the exam i failed last semester togather with this semester's course exam (Electical Engineering 1+2)

:-p:-p :devil::biggrin::blushing::mad::eek::bugeye::cool::zzz::cry::approve:
 

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