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Finding the impedance of circuits.

  1. Jan 21, 2013 #1
    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):

    tFqniA0.png

    t5RyQE3.png

    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. jcsd
  3. Jan 22, 2013 #2
    Seems all good to me.
     
  4. Jan 22, 2013 #3

    rude man

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    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.
     
  5. Jan 22, 2013 #4
    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):

    4RHtjSy.png
     
  6. Jan 22, 2013 #5
    Whoops, messed up a sign. Should be this:

    yD2t7Ia.png
     
  7. Jan 22, 2013 #6

    rude man

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