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

1. Feb 28, 2013

nchin

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. Feb 28, 2013

CWatters

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
3. Feb 28, 2013

nchin

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))?

4. Mar 1, 2013

nchin

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?

5. Mar 1, 2013

CWatters

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

6. Mar 1, 2013

CWatters

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.