Lecture -- Lorentz Oscillator Model

[@vlad7780]

Thank you! The best explanation of this topic in KZbin.

[@empossible1577]

Thank you!

[@alatishewasiu7366]

Thank you, this is one of the best piece

[@Sagivbh]

Very good video explanation! Thank you.

[@ilyassvino1154]

greatings from Morocco

[@empossible1577]

Hello Morocco!!! I love hearing where people are from and what they are doing. It is great to see the videos reaching into Africa! Some day I hope to visit Morocco. Have seen pictures of the coastline, Sahara, and places like Ouarzazate-Zagora-Tinghir.

[@colonelmustang337]

Thanks, this really helps!

[@HornWilliam]

Very good.

[@mauriciodias458]

Excellent video, as usual. I have a question though, regarding the animations on slides 8 and 17. When the field is at its peak (positive), I would expect the electron cloud to move to the opposite direction, but the animations show the opposite behaviour, as if the cloud were composed of positive charges. Am I missing something? Should I consider a delay to correctly interpret the animation?

[@empossible1577]

Great observation! I think my animation is misleading and I should have inverted the blue wave.

[@mauriciodias458]

Hello again. I got confused with a passage in the derivation of the susceptibility expression. Why do you consider the Fourier transform of the derivative with a minus sign? As far as I am concerned, in most references it should be "j omega", not "- j omega". It impacts the sign of the gamma term in the denominator. In Balanis' book, such sign is positive, in line with the usual Fourier transform of the derivative. I would appreciate if you could shed some light on the subject.

[@empossible1577]

It is merely a sign convention thing. The majority of the literature on EM properties of materials that I was using for my class used the positive sign convention so that I what I used for that derivation. BTW, here is a summary on the sign convention in electromagnetics and photonics that may help... empossible.net/wp-content/uploads/2018/03/Summary-of-EM-Sign-Conventions.pdf Also, this summary is posted on Electromagnetic Field Theory class at the following link in Topic 3: empossible.net/academics/emp3302/ Hope this helps!!

[@mauriciodias458]

@@empossible1577 Sure, I thought it could be something related to that. Thanks for the prompt feedback.

[@tiberiusgeorgescu9315]

Thank you.

[@igboukwu]

I was just wondering what you used to simulate the oscillating atom in an external electric field.

[@empossible1577]

Blender...while it is possible to make it an actual simulation in Blender, it is just an animation.

[@igboukwu]

@@empossible1577 Thank you.

[@hamidk4772]

Great 👍.

[@adelassad724]

Excellent Explanation!, However, I have a question; if (wo) is the natural frequency of the system then what is the plasma frequency (wp)? since you mentioned also that the plasma frequency is also a constant?

[@empossible1577]

Great question! First, let me point you to the official course website. I recommend using this as your main portal to the videos. From the website you can download the latest version of the notes, get links to the latest version of the videos, and and get access to other resources. empossible.net/academics/emp6303/ At some high frequency, usually in the ultraviolet, materials experience a bulk oscillation of their electrons when they are pushed by an oscillating electric field. More practically, we tend to think of materials has behaving like the material they are below the plasms frequency and behaving like a vacuum above the plasma frequency. It is a very slow and smooth transition so this way of thinking is somewhat crude. Watch the video of Lecture 2f for a full explanation.

[@nesslange1833]

11:31 If we were to inverse Fourier transform this expression r(omega), what do we get? A decaying wave r(t)?

[@empossible1577]

Yes. Like a decaying sine wave a bit like ringing a bell. It is the impulse response.

[@asmaaahmed5755]

thank you so much, I am really interested in these lectures so please could I ask how many lectures are you published concerning dielectrics? and where can I find all of them combined?

[@empossible1577]

Thank you! I am very glad you are finding the materials helpful. Here is a link to all the courses I offer: empossible.net/academics/ As for discussion of the dielectrics themselves, I cover that in Topic 3 here: empossible.net/academics/emp3302/ and in Topic 2 here: empossible.net/academics/emp6303/ I later build on these concepts to talk about mixtures, metamaterials and photonic crystals in Topic 5 at the same link immediately above. Hope this helps!

[@asmaaahmed5755]

@@empossible1577 Sure helpful thank you so much

[@kavithasenthilkumar4533]

Sir did you make video for multiple resonance

[@empossible1577]

Yes! You might want to access the course through its website. You are looking for Lecture 2g. Hope this helps! empossible.net/academics/emp6303/

[@kavithasenthilkumar4533]

Thank you sir

[@nzuckman]

7:10 😂😂😂😂😂😂

[@txominpenasantacruz2472]

I invite you to consult (simple atomic oscillator) and (Átomos de Santa Cruz)

[@empossible1577]

What did you have in mind? You can e-mail me directly at emprofessor(at)empossible.net