# Homework Help: Basic circuits and ohm's law

1. Sep 27, 2014

### homo-sapiens

1. The problem statement, all variables and given/known data
Determine the power absorbed by the 15 ohms resistor, see circuit below.(the ix, i1, and i2 are things i added)
http://puu.sh/bQyEk/5f47888b03.png [Broken]

2. Relevant equations

the KCL law
the KVL law
the ohm's law
power = voltage * current

3. The attempt at a solution
I calculated the whole resistance of the second branch first. then I found the relationship between current ix and current i since the voltage of a loop = zero. I then calculated the current using the KCL current law. i then found a relationship between current i1 and current i2. I calculated current i2 and used the power = resistance * current * current.
My answer is way off from the answer key, and I would like to know what I did wrong??

http://puu.sh/bQyK1/715544a6a1.png [Broken]

Last edited by a moderator: May 7, 2017
2. Sep 27, 2014

### jz92wjaz

Your approach looks good. It looks like you miscalculated ix = 36/51*(.425).

3. Sep 27, 2014

### homo-sapiens

ops!! that was a minor mistake on my part, but the answer is still not right with the answer key......
http://puu.sh/bQDw6/e03756b3b0.jpg [Broken]

Last edited by a moderator: May 7, 2017
4. Sep 27, 2014

### jz92wjaz

The answer key is wrong. It comes up with v = -19 when solving for -2 - 2*v/6 = v/8.5 + v/6 + v/6, which is clearly incorrect (I calculate v = -2.55).

5. Sep 27, 2014

### homo-sapiens

OH!!! thank you so much for clearing this up for me. aw, never thought the answer key would be wrong. I guess I should believe in my methods more often. thank you again.

6. Sep 27, 2014

### jz92wjaz

You're welcome! It's always unnerving when the answer key is wrong, but it's nice when you can spot the mistake so you know for sure.