Intro to Complex Numbers for EE

[@godisjustlikejesus5734]

Great description of all 4 EE coordinate systems

[@aa1ww]

A couple of points .... It works nicely to call i or j the sqrt(-1) but, in actual fact i, or j, for that matter is not equal to the square root of -1. If you think about it, sqrt(-1) * sqrt(-i) can be written as sqrt(-1 * -1) which would be 1. Mathematicians and EEs define the i or j as i^2 = -1. Also the arithmetic solutions of AC circuits work only for steady-state sinusoidal excitation; still very useful.

[@thedoubleeguy]

This is an awesome comment. Thanks for the added insight as well as clarification.

[@camgere]

Complex impedances are one of the joys of electrical engineering. Great introduction! At 3:30 you could show the point Voe^jwt going around a circle of radius Vo at a frequency of w radians/sec = w/2pi cycles/second. In linear systems sinusoidal inputs create sinusoidal outputs of a (usually) different magnitude and phase. Complex numbers have magnitude and phase. So Vin = Vine^jwt and Vout = Voute^jwt+theta. Vout/Vin is the complex impedance and theta is your angle. 6:00 Frequency response can be determined by simply trigonometry rather than differential equations. Something easy for once!

[@thedoubleeguy]

Yes! Thanks for the suggestions my friend, I'll look into making a video with this type of visual explanation as well!

[@shashikantsingh6555]

Wow... Excellent and to the point video cleared all of my doubts... Keep it up

[@hydro2827]

I loved the video. I’m currently in my first semester of ee classes and having a little difficulty with transient analysis. Where would you suggest I get some help with this outside of the classroom?

[@thedoubleeguy]

Thanks my friend, there are a number of resources I would recommend. If you have access to an oscilloscope I would recommend building a small RC circuit with a breadboard to observe transient phenomena. You can also simulate these responses in software such as LTspice. A great book to reference would be Practical Electronics for Inventors which I believe there is a free pdf for online. Let me know if this helps and good luck in classes.

[@keithto5990]

Some said inductance reactance should be -90 deg, is it correct?

[@thedoubleeguy]

inductive reactance as displayed in this model should correctly say +90 degrees because j(omega)L has a j in the coefficient. This gives it a positive 90 degrees according to this model. I would refer to the book "Practical Electronics for Inventors" by Paul Scherz and Dr. Simon Monk. They have more an even more in depth explanation.

[@IanFosterSmith]

I find this very confusing from the outset. If i is the square root of minus one, why do we now need j?

[@nelkabosal]

EEs often use "i" for current, so we use "j" for sqrt(-1)