Solving Circuit Analysis Problem: Find V - Power of 5Ω Resistor is 20W

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Discussion Overview

The discussion revolves around solving a circuit analysis problem involving a 5Ω resistor with a power absorption of 20W. Participants explore the relationships between voltage, current, and resistance to find the total voltage supplied in the circuit.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Technical explanation

Main Points Raised

  • One participant states the power absorbed by the 5Ω resistor is 20W and uses the equation P = V²/R to find the voltage across the resistor, initially calculating it to be 10V.
  • Another participant asks about the current flowing into and out of the node above the 5Ω resistor, prompting further exploration of the circuit.
  • A participant calculates the current through the 5Ω resistor to be 2A and combines the 2Ω and 3Ω resistors in series to find a total current of 4A, leading to a total voltage calculation of 18V.
  • Participants confirm the calculations and express satisfaction with the solution process.

Areas of Agreement / Disagreement

The discussion shows a collaborative effort to solve the problem, with participants generally agreeing on the calculations and methods used, although the final total voltage calculation is presented without explicit consensus on the approach taken.

Contextual Notes

Some assumptions about the circuit configuration and the behavior of the components are not explicitly stated, which may affect the interpretation of the results.

Who May Find This Useful

This discussion may be useful for students or individuals seeking assistance with circuit analysis problems, particularly those involving power, voltage, and resistance relationships.

hackett5
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Homework Statement


Hello, I was hoping someone could walk me through the steps to solve this problem:

The power absorbed by the 5Ω resistor is 20W. Find V
http://img191.imageshack.us/img191/6411/14966985.jpg


Homework Equations


V= I x R
P = V2/R

The Attempt at a Solution



I first found the voltage across the 5Ω resistor to be 10V using V= I x R and substituting 20W / V for the current. How do I find the total voltage supplied?
 
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You know the voltage across the resistor, good. So you know the voltage of the node above the 5Ohm resistor. Can you tell us how much current goes in and out of that node? Where does it come from? Where does it flow to?
 
Well, using I= V/R, I get 2A (I1) going through the 5Ω node. The 2Ω and 3Ω resistors are in series so I can combine them as 5Ω. So through that node the current would also be 2A (I2) and voltage would be 10V. Then I2 + I1= Itotal or 2A +2A= 4A? The total resistance would be 2.5Ω and voltage = 10V?

So the total voltage would be: V= 10V + the voltage across the 2Ω resistor.

V= 10V + (2Ω x 4A)
V=18V
 
Bingo!
 
Awesome! Thanks for the help
 

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