I'm still stuck on this task:

enter image description here

And I'm trying to calculate Vth. I've calculated:

enter image description here

And the Vth equation is: enter image description here

My problem now is that I want to convert from rectangular form to polar form for 100j/100 + 100j. I can't seem to get it right. I tried multiplying with the conjugate, however I just got (j). I want to convert it to polar form so that I can multiply the amplitudes and add the angles. However I'm stuck.

Could someone help?

Update: I solved the upper part. Now I need help with time-domain. Please look below:

I've got a hard time understanding how to calculate the time domain. I've found the Vth and Zth like so:

enter image description here

Note: Ignore the white markings, it was written in swedish, therefore I tried to hide it so it wouldn't led to confusion.

And this is how far I've gotten to be able to find the time domain: enter image description here

I don't know how to find the angle and how to proceed with finding the time domain so that I can draw a schematic of it.

I would appreciate some help. Thanks!

  • 1
    \$\begingroup\$ Well, you do multiply with the conjugate so show your working for this so we can see where your math went wrong. You should get 0.5 - j0.5 for the transfer function BTW. \$\endgroup\$
    – Andy aka
    May 13, 2020 at 10:30
  • \$\begingroup\$ @Andyaka Hi, I missed that j^2 = -1. So that's why I only got (j) in the end. I got it to be 0.5j+05 in the end. \$\endgroup\$
    – Vetenskap
    May 13, 2020 at 10:45
  • \$\begingroup\$ @Andyaka I made changes to the post instead. \$\endgroup\$
    – Vetenskap
    May 13, 2020 at 14:33

1 Answer 1


You can use the arctan function to find the angle, given the imaginary and real parts.


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