We always enjoy a [FesZ] video and we wonder if the “Z” stands for impedance? That’s the topic of his latest video series: measuring impedance with LTSpice. Of course, he also does his usual thorough job of mapping the virtual world to the real one. You can see the video below.
It is simple enough. Impedance is very similar to resistance. That is to say, we have a ratio of voltage and current. However, since it is an AC quantity, you need a complex number to represent it and there is an associated phase shift.
We learned the mnemonic phrase “ELI the ICE man” to help remember that voltage (E) leads current (I) in inductors (L) and the reverse for capacitance (C). Things get more complex — no pun intended — when you mix capacitors and inductors which requires a vector addition.
Keep in mind that complex numbers can appear as a real and imaginary part — in this case, real resistance and an “imaginary” reactance or you can show a magnitude and a phase angle. Both representations have their uses.