Lecture 3d -- Lossy Dielectrics

This lecture discusses electromagnetic waves in lossy dielectrics and the meaning of the wave various wave parameters when they are made to be complex.

[versatile_gentlemen]

It seems there are very few people in this world who are excellent teachers as well as researchers. And you are one of those. Thank you for sharing these lectures.

[retefotonica]

You are amazing! I understood everything I've been confused about

[ManojKumar-cjoj]

Your channel + your notes are a blessing for every graduate student.
This shows your hardwork and creativity .
You Will get a special place in heaven 😁❤️❤️❤️❤️❤️❤️

[inboccaallupo]

I am now convinced that these are the best videos to learn electromagnetics. I have only one doubt: When we have very high conductivity this means if the wave passes through it will get very fast attenuated by the conductive losses, but since there is a reflection from this lossy medium the wave actually doesn't experience the losses. Firstly, why does it apply more for lower frequencies? Also, in general, we get reflection when there is an impedance change in the medium, so does it mean that we assume we enter from a medium with a particular impedance to a highly conductive material implying a different impedance ( assuming we have almost all reflected the difference should be big). So is conductivity proportional to the characteristic impedance of the medium ( if this is possible to answer with these complicated equations)? Lastly, I can not express how grateful I am for these lectures - enormous knowledge with a very intuitive and straightforward approach.

[isee.]

Beautiful! Thank you so much! Professor Rumpf!

[한두혁]

Amazing! I have a question sir. in 3:27 you have complex permittivity. But in some text book they write are these same equation?

[trejkaz]

I'm curious about how Snell's Law is interpreted when the refractive index is complex. I've heard of three separate interpretations so far:
1. You ignore the imaginary part and use just the real part when calculating the angle of transmission, then use the imaginary part only for calculating decay.
2. You do all the maths keeping the complex values, get a complex angle out, and then somehow derive the real angle from that.
3. You use the imaginary part (and the angle of incidence) to manipulate the _effective_ refractive index in the material, and then use that to compute everything. And presumably you still get to choose whether to do #1 or #2 after doing this. So maybe this makes 4 possibilities; or maybe one of these possibilities turns out the same as the maths you'd get doing #2.

[khaledalhorani]

I've reached to the point that I like your video even before watching it :D

[alexandermuller]

Thank you, Lots of very good stuff in here. Still i have a question regarding the complex permittvity. You mentioned that one should not mix complex permittivity and real conductivity. Here is my question: the imaginary part of the complex permittivity represents the losses. But these are only losses due to sigma. What about the losses due to changing of polarization in dielectric material in case of dynamic E-Fields? They also have to be included into the imaginary part or not? For fast time varying E-Fields there should be phase difference between Polarization field and E field or not?

Also, if my omega is 0, sigma/omega becomes infinite? So for DC i have infinite losses? Im a bit confused.

[karielf]

Excellent course, thanks a lot. very clear and well summurized

[TheMorningbirdFoundation]

Where is the energy going in a lossy material?

[Astartos]

Thanks so much for this video, it was very helpful. Sorry if I’m misunderstanding but does this mean that for a lossless material, there will never be dispersion? Are loss and dispersion intrinsically connected?

[اسلامكمال-خذ]

Dear sir, do you have a video about losses in capacitor and inductor?

[egghead]

Since the speed of light is 1/sqrt(mu*ep), doesn't a complex dielectric imply the lossy part of the wave moves into a new dimension? The output is in units of meters/sec, not heat. Is ehat we experience as heat loss the manifestation of the energy moving into a new dimension?

[meghjitmajumder]

Fantastic video once again... But out of the context, I'd like to say that yesterday I noticed that there is one particular area in electrostatics which I don't understand really well and that is Method of Images. So, it'll be very kind of you, if you think of making a video on it.

[charanpreetiitd]

Sir, great lecture, thank you, but I'm very confused about the correct mathematical formula for calculating intrinsic impedance of a lossy medium, which has both permeability and permittivity as complex numbers. I have been using Zin = Zo * sqrt(μr'-μr''/εr'-εr'') * tanh [ j 2πf.d. I then use it to calculate Reflection loss as R = 20.log (Zin-Zo)/(Zin+Zo). However, my answers never match that of the authors in several published articles, which quote the same formula. This is a lengthy explanation but I wanted to be explicit to be able to get an answer I have been searching for so long. Would really appreciate your response, possibly with a quick problem example. Thanks in advance.

[ManojKumar-cjoj]

In good conductos E field leads H fields by 45°

[motobacktoconstitution]

Thank you shearing sir. I couldnt time to watch all. Please make shorter video or please lead me to short e r video please I wanted understand what you are saying but too long I have to do my job. So couldn't here all sorry.