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Dissipation of Power by Resistors

  1. Mar 16, 2009 #1
    1. The problem statement, all variables and given/known data

    untitled.jpg

    2. Relevant equations

    P=IV
    I=V/R
    P=(V/R)V
    R=V2/R

    3. The attempt at a solution

    PR1: 122/12=12
    PR2: 144/18

    I'm not sure what to do from here. Thanks for any input and help!
     
  2. jcsd
  3. Mar 16, 2009 #2

    LowlyPion

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    Homework Helper

    Maybe start with how much current is passing through the resistors?

    Your attempt incorrectly tried to use the total Voltage of the supply across the resistors singly. The question wants to know the power dissipated by each resistor.

    Once you have the current then won't the power for any resistor be P = I2R ?
     
  4. Mar 16, 2009 #3
    I=V/R
    Rtotal=12+18
    I=12/30
    PR1=RI2
    PR1=12*[tex]\frac{2}{5}[/tex]*[tex]\frac{2}{5}[/tex]
    PR1=48/25

    PR2=[tex]\frac{72}{25}[/tex]=2.88
    Thanks!
     
  5. Mar 16, 2009 #4

    LowlyPion

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    Homework Helper

    There you go. Good job.
     
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