Solving for Resistance in a Circuit

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SUMMARY

The forum discussion focuses on solving for the unknown resistance R in a circuit with an equivalent resistance of 40 ohms between points A and B. The initial calculation incorrectly resulted in a negative value for R due to algebraic errors. The correct approach involves re-evaluating the equation 28 = [(1/55) + (1/R)]^-1 to find the accurate resistance value. Participants emphasize the importance of careful algebraic manipulation in circuit analysis.

PREREQUISITES
  • Understanding of Ohm's Law and circuit analysis
  • Familiarity with series and parallel resistor combinations
  • Basic algebra skills for solving equations
  • Knowledge of equivalent resistance calculations
NEXT STEPS
  • Review the principles of series and parallel resistor combinations
  • Practice solving circuit resistance problems using Kirchhoff's laws
  • Learn about the implications of negative resistance values in circuits
  • Explore advanced circuit analysis techniques such as Thevenin's and Norton's theorems
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Students studying electrical engineering, hobbyists working on circuit design, and educators teaching circuit analysis concepts.

whoopie88
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Circuit Resistance Problem!

Homework Statement


The equivalent resistance between points A and B of the resistors shown in the figure below is 40 . Find the value of resistance R.

21-30.gif


Homework Equations


All circuit formulas.

The Attempt at a Solution


40 - 12 = 28
28 = [(1/55) + (1/R)]^-1
R = -27

Help!
 

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whoopie88:

Your equation for the unknown R is OK, but a mistake in your algebra has led you to find a negative solution. Retry your calculations carefully and see if you can't solve your equation properly.
 

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