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Check my work please? Circuit analysis, resistors in parallel, help!

  1. Feb 28, 2013 #1
    Can someone check my work for me please? I'm pretty sure i made a mistake with the sign convention but i'm not sure which sources are supposed to be negative. help!

    Problem:
    http://imageshack.us/a/img201/339/circuitzz.png [Broken]

    My solution:
    http://imageshack.us/a/img191/8049/circuitz.png [Broken]

    The top half is me solving the left side the circuit and the bottom half is the right side of the circuit.
     
    Last edited by a moderator: May 6, 2017
  2. jcsd
  3. Feb 28, 2013 #2

    CWatters

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    Re: Check my work please? Circuit analysis, resistors in parallel, hel

    The basic calculations/magnitude look fine to me. However the passive convention says that the power of the sources would be negative. So for example the power of the 60V source is -0.6W.

    Examples..
    http://circuits.solved-problems.com/456/problem-1-15-power-independent-sources/ [Broken]
     
    Last edited by a moderator: May 6, 2017
  4. Feb 28, 2013 #3
    Re: Check my work please? Circuit analysis, resistors in parallel, hel

    so if the power of the 60v source is -0.6, does that mean the power in resistor 1 is -0.1 and the power in resisor 2 is -0.5? since power supplied = power dissipated?? (-0.6 = -0.1 + (-0.5))?
     
  5. Mar 1, 2013 #4
    Re: Check my work please? Circuit analysis, resistors in parallel, hel

    ok nvm i figured it out,, but am i solving r3 and r4 correctly?
     
  6. Mar 1, 2013 #5

    CWatters

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    Re: Check my work please? Circuit analysis, resistors in parallel, hel

    No the power dissipated in the resistors is +ve. You write something like..

    Power in source + Power in load = 0

    -0.6 + 0.1 + 0.5 = 0
     
  7. Mar 1, 2013 #6

    CWatters

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    Re: Check my work please? Circuit analysis, resistors in parallel, hel

    I threw away the scrap paper I used yesterday but yes I got the same power disipation as you for R3 and 4.
     
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