Circuit analysis - proportionality

Mohdoo · May 23, 2011

Homework Statement

Circuit schematic with a 40 V source on the left and a 28 A source on the right, resistors labelled 3 ohm, 40 ohm, 2 ohm, 4 ohm, 1 ohm and 2 ohm, under the printed problem text about finding power in the 4 ohm resistor.

Handwritten-annotated photo of a printed circuit problem, Problem #4: find Io using the unit output method, with resistors 130, 10, 60, 34, 72, 8, 20 and 10 ohms and a 600 V source.

Homework Equations

First problem:

Handwritten circuit analysis on lined paper: a series of simplified resistor networks reduced step by step from a 40 V source and 28 A source to 24 A, with a 2.5 ohm total resistance and V1 = IR = 60 V, giving power 900 watts.

Second problem:

Handwritten circuit analysis on grid paper: a 60A current source feeding five parallel resistors (10, 200, 114, 200 ohms) with I_o labelled at the last branch, and a reduced circuit with 8.789 ohm equivalent in series with 20 ohm.

The Attempt at a Solution

I assume it is acceptable to lump this section into the previous one, as I believe they go hand in hand in this case. My apologies if not.

I am definitely a lot more lost in the second problem than I am in the first. I feel like I may have gotten the first one done just fine, but I am pretty stumped on the second problem. I am stuck at the point where I am at :(

In an example, my professor said to just label the source as I_s and then to assume I_o as 1v, then work from there, but that was an example where we were hoping to find voltage. I wasn't sure if I should do the same, but with current this time. Very confused :(

Any help would be greatly appreciated :)

Cheers!

jegues · May 24, 2011

How are you adding the 34 ohm resistor with 72 and 8 ohm resistors?

Certainly the 34 ohm resistor is not in series with those two.

gneill · May 27, 2011

In the first problem you're supposed to be looking for the power dissipated by the 4 Ohm resistor, but in your very first step (Thevenin transformation) you've eliminated the 4 Ohm resistor as a separate component. The 4 Ohms that you found the power for in your final step was not the original 4 Ohm resistor, but in fact the sum of the 3 and 1 Ohm resistors!

Circuit analysis - proportionality

Homework Statement

Homework Equations

The Attempt at a Solution

Discussion

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