EM Waves

Electromagnetic waves. EM spectrum, energy, momentum. Electric field and magnetic field. Doppler shift. Polarization. Song at 47:47 is "On the Border" by the Eagles.

[mog]

I fell asleep watching something and somehow ended up on this video when I woke up

[mcpr]

Electromagnetic Waves travelling from my screen to my retina are teaching me about themselves.

[MrBendybruce]

I know this is an old lecture, but honestly, it's just so damn good. Not only does it teach the fundamentals in a clear and easy to understand way, but it provokes thoughts and ideas for the curious listener. This is a real gift to the internet.

[byrontakahashi]

I’m now 66 years old and remember loving math thru high school. Might be my only regret in life that I followed other successful paths. Magnetism and EM waves are the most intriguing things I’ve ever seen! Thanks for your sharing, can you imagine just starting college now?! Your drawings and explanations are awesome and inspirational! Thank you!

[malikamajjoud]

I also found this video by falling asleep and then waking up 20 minutes in 😂. But this lecture is great! Everything makes perfect sense and is very accessible. What a time to be alive where you can watch a lecture this quality at 7am on the other end of the planet

[sarcosmic]

The effortless reflected handwriting is really impressive and neat! It’s fascinating to watch the writing appear almost as if by magic

[Ejeby]

41:27 equation: electric and magnetic energy density
1:01:30 equation: what is the total power output of the sun
1:14:30 lens can be intensity of the sun
1:29:00 righthand rule
1:32:00 red shift, blue shift 1:35:15 why is this only true when v is much less than the speed of light; what are the complications when the relative velocity approaches the speed of light[[?]]
1:36:00 equation for rotating galaxy 1:39:20 the galaxy is moving away faster than its spinning, so both points (including the one moving "toward" earth) are red-shifted
1:43:15 polarization defined as direction of the [[electric field]]; there are only 2 possibilities (for lasers and what else[[?]]): horizontal or vertical polarization = "defined polarization" [[?]]; incandesecent sources, like sunlight or a lightbulb, have all the angles = "random polarization"
1:45:35 glare tends to be dominantly polarized in one direction [[?]] how come it never happens that when you put on polarized sunglasses you end up filtering out the object's light and keep only the glare[[?]]
1:48:00 [[electric field]] peak value 21.7millivolts per meter ; power = energy per time ; intensity = power per area
1:57:15 sunlight pushes on you a little bit ; "radiation pressure" refers to momentum transfer between wave and radiated object aka "absorber" ; equation of momentum transfer
2:00:25 "this is kinda like what we talked about..." [[?]]
2:01:00 Force = Delta P (pressure) over Delta T (time) ; pressure = average intensity / [[speed of light]]
2:03:40 [[?]]
2:04:00 inside spaceship a sheet of [[teflon]] foil or [[mylar]] that expands when it gets into outer space; this is called a solar soil ; mylar is a big reflector: the light that comes in hits the solar sail and pushes the spacecraft
2:06:45 intensity of sunlight on earth is roughly 1400 Watts per square meter; this is about as much as a hair dryer
2:09:35 1/4 lb ~= 1 Newton
2:11:00 [[solar sail]] keeps accelerating with weight of a marble forever

[omealyjackson]

This method of teaching is absolutely beautiful. I love his approach. The way he builds up from the basics and expands on it is simply amazing. One of the best teachers out there.

[jemmari]

Whether you like or hate a subject is always on the teacher. Good teachers get your attention just by the way they teach and how much they belive in what they teach. This guy is a good teacher and interesting to hear. All teachers should teach like this. Thanks, you are great.

[alondralalala]

All my teacher does during the pandemic is post the Hw and put youtube videos to teach us. You have literally been saving my grade!

[michaelstone]

I wish more physics professors were like you. This is actually really interesting.

[korenaboyd]

Studying for my MCAT and thought I would NEVER understand waves. WOW. Thank you Dr. Anderson for making learning physics so accessible and rewarding <3 truly grateful for your videos!

[ardenkwong]

GENIUS! Someday ALL university physics "conversations, lectures, and problem solving" will be taught this way! Learning Glass technology, mirror image of Dr. Anderson "facing" his students, and his enthusiasm, explanations, texts, and illustrations projected normally -- all this makes learning personal, inviting, clear, and mutually fun for BOTH sides of the Glass! LOL for Dr. Anderson's "reverse-image-corrected" right hand rule explanation at 1:22:27 in which he has to use his actual left hand (with wedding ring) to project the image of his right!! This is a game changer for higher learning (like Dick Fosbury's "then-new-approach" to high jumping in 1964)!!!

[ElPasoTubeAmps]

I think your lecture is wonderful. I understood this as a child (I am now 72) as I was coached by my uncle, a chemist at ORNL, but have found few people that can comprehend or care about such things. But we love what we love. I would like to just randomly add that heating the concrete you mentioned around 1:15:00 is something I did a few years ago with a carbon arc. I think it was arcing at about 36V @ 70A. It ended up being a bad idea as apparently the water vapor in the concrete caused the hot-spot to explode (after becoming red hot) and blow very hot pieces of concrete all around and into my face. I was not injured seriously but it taught me a lesson that extreme temperatures (or anything else) can do unexpected things. Lastly, even after all these years, I still enjoy a good presentation like you posted here. I know it has been seven years since you posted but please keep up the good work and enjoy life. I know it would be subjective but it would be interesting to plot real-time ageing years with perceived ageing years as we grow older.

[MrCrash]

Apparently, I'm not the only one who fell asleep on YouTube and woke up to this. It's an amazing video to wake up to tbh. YouTube algorithm doing it right!! I went on to get my Master's degree in Information and Digital Communication, but I have always had a passion for physics. This goes right in the feels! Thank you for this amazing course!

[mpsdelhi]

Brilliant! The teacher and teaching style. Engineering and science students of today are so fortunate to have access to such material and great teachers like Prof. Anderson! Keep strong, Sir!!

[enochbrown]

Wow, Dr. Anderson is a great teacher. He makes physics so clear and understandable. What a gift he is to teaching and science. When I first started watching this video, I thought, OMG an academic is about to make the difficult to understand even more difficult and I just may be wasting my time. Was I wrong! What a surprising blessing, for sure.

[bennyhollis]

1 hr in and I just realized that you're writing everything backwards from right to left.. The amount of practice this must have taken is a dedication to teaching that should be commended. Thank you!

[muhammadomarkhayyamkhan]

This teacher is not Just a Teacher he is a Scientist. wonderful teacher.

[s.mendez]

Dr. Anderson, the tools for teaching this make learning so much easier to understand, compared to physics taught in the 80's. So appreciate the cadence of your teaching. Just awesome! Your students are blessed to have you as an instructor. Thank you.