# Homework Help: Simple AC Analysis

1. Nov 4, 2006

### verd

Hey,

This is a problem involving loop/mesh analysis on an AC circuit. I'm less confused about the circuit theory, I'm more confused with how to solve the resulting matrix. I get 4 equations with 4 unknowns... Which is something I'm accustomed to solving, but there are three different types of terms. Imaginary numbers, real numbers, and the phasor format (magnitude<angle - 4<60)

Here's the problem. I solved it the same way this person did, I'm just stuck on the matrix.

http://synthdriven.com/images/deletable/EEN201-17.jpg [Broken]

Thanks!

Last edited by a moderator: May 2, 2017
2. Nov 4, 2006

### teknodude

Doing that by hand along with the complex numbers and phasers are a real pain, but not impossible. Just convert them all into complex or phasor fomat.

If you have a TI-89 or Ti86, then you can just punch those numbers that you have there into a matrix and it will solve it for you. I believe the Ti-83 has some limitations on the phasors and complex numbers in matrices, but i'm not sure. Also matlab will work.

3. Nov 5, 2006

### verd

How do you convert from phasor format into imaginary numbers??

4. Nov 5, 2006

### teknodude

I was hoping you wouldn't ask that, but I guess your instructor isn't going to let you use a calculator on a test.
Your textbook should have an explaination of how to do it. Its about the same the same way as breaking a vector into components. I'm a bit rusty on circuits and my notes and textbook are 400 miles away . Hopefully someones else will comes along and help.

Simple rough example

(4<30)

4 cos 30 = 3.46
4 sin 30 = 2

z = 3.46 + 2j

It's easier to add, subtract, multiply and divide in complex format than phasor.

5. Nov 6, 2006

### doodle

Since $I_2 = 4 \angle 30$, this is a system of 3 (instead of 4) unknowns. It would be nice if you can further reduce that to 2 unknowns since systems of equations with 2 unknowns are very much easier to solve than 3.

As far as the solution goes, you'd perhaps need to convert all the terms into the complex equivalent as suggested by teknodude.

I think it's easier to add and subtract in complex form, but multiplication and division are easier in phasor.

6. Nov 6, 2006

### teknodude

Crap.. wtf was I thinking. Yea doodle is right on that.

7. Dec 8, 2006

### dh19440113

teknodude
Please, can you explain how to punch the matrix into a ti 89, it will help save alot of time and possible mistake.
Thanks

8. Dec 8, 2006

### teknodude

Read the instruction manual or go to the ti website and download it. I rarely use my 89 except for integration checking. I like my aging ti86 more.