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

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SUMMARY

The problem involves calculating the total voltage supplied to a circuit with a 5Ω resistor absorbing 20W of power. The voltage across the 5Ω resistor is determined to be 10V using the formula V = I x R, where the current is calculated as 2A. The total voltage supplied to the circuit is found to be 18V by adding the voltage across the 2Ω resistor, which is derived from the total current of 4A flowing through the series resistors.

PREREQUISITES
  • Understanding of Ohm's Law (V = I x R)
  • Knowledge of power calculations (P = V²/R)
  • Familiarity with series circuits and current flow
  • Ability to manipulate circuit equations for voltage and current
NEXT STEPS
  • Study series and parallel circuit configurations
  • Learn advanced circuit analysis techniques using Kirchhoff's laws
  • Explore power distribution in electrical circuits
  • Practice solving circuit problems with varying resistor values and configurations
USEFUL FOR

Students studying electrical engineering, circuit designers, and anyone looking to enhance their understanding of circuit analysis and power calculations.

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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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