# Homework Help: Finding the impedance of circuits.

1. Jan 21, 2013

### RobLikesBrunc

I'm currently taking a junior circuits lab that expects familiarity with impedance (my intro E/M course never covered it), so I just want to make sure I did these two impedance problems correctly (the second one asks merely for a formula, so no calculation was done):

Later in the assignment, I'm also asked the plot the phase of Z1 as a function of frequency. For that (letting Z1 = x + yi), the phase is just arctan(y/x), right?

Thanks.

2. Jan 22, 2013

### voko

Seems all good to me.

3. Jan 22, 2013

### rude man

Looks good to me also.

Caution: in computing arc tan (y/x), be sure to retain the signs of x and y to determine in which quadrant the angle belongs. Arc tan b/(-a) is not the same angle as arc tan (-b)/a.

4. Jan 22, 2013

### RobLikesBrunc

There was actually a little mistake--on the last line I replaced the -i with -1 :P

Anyway, I was actually plotting the phase over 10^6 frequency range, so which quadrant to place it in is a non-issue. It looks pretty neat too (note the x-axis is logarithmic):

5. Jan 22, 2013

### RobLikesBrunc

Whoops, messed up a sign. Should be this:

6. Jan 22, 2013

### rude man

I was a about to draw your attention to that! Now it's OK.