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Electrical Energy Dissipation Across Resistors

  1. Sep 24, 2013 #1
    1. The problem statement, all variables and given/known data

    (image attached)
    A). What is the total rate at which electrical energy is dissipated in the 5.0−Ω resistor?
    B). What is the total rate at which electrical energy is dissipated in the 9.0−Ω resistor?
    C). What is the power output of the 16.0-V battery?
    D). At what rate is electrical energy being converted to other forms in the 8.0-V battery?


    2. Relevant equations

    P=V_ab(I)=I^2R=V_ab^2/R

    3. The attempt at a solution

    I can't figure this out at all. For part A, I need the voltage difference and the resistance. How would I find the voltage difference? And does the 5 ohm resistor mean that the resistance is 5 over the resistor? In which case I need to find the voltage drop across the resistor. How do I do this?
     
  2. jcsd
  3. Sep 24, 2013 #2

    phinds

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    no image attached
     
  4. Sep 24, 2013 #3
    Sorry, attached it now!
     

    Attached Files:

  5. Sep 24, 2013 #4

    phinds

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    Just sum up all of the voltage sources around the loop and all the resistances, since they're all in series, and you'll have the current around the loop. Can you take it from there?
     
  6. Sep 24, 2013 #5
    Ok, so I added up the voltages (24V) and added up the resistance (17 ohms). I then did V/R to get I=1.412A. Then, I used the equation P=V_ab * I and got P=120W, but it is wrong. What am I doing here?
     
  7. Sep 24, 2013 #6

    phinds

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    You are not taking into account the direction of the voltages.
     
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