Accelerating Charges Emit Electromagnetic Waves - "Light" - Radio Antennas! | Doc Physics
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- Опубліковано 10 лют 2025
- Every charge that accelerates emits light that indicates how it has been accelerating. This can be used for radio and other long-range communications!
Dude this is the best explanation of how electromagnetic waves are emitted. You killed Yale and Stanford . . . . A big thank you from an engineer who uses this stuff on the daily and now understands it better!!
Agreed, one of the better explanations available
This is only repeated story without thinking. Antenna is reactive part of system , and all science story is wrong. Is impossible to have max value E and B field at same time, also current and voltage. Ok, we use horizontal plane to represent B field , but that do not have any sense with phase shift, only with interpretation. Write new diagram, with B min at point of E max and that is correct. Only book with that presentation is correct, but maybe only few contain valid picture.
+ Electrical Disturbance - I think you are correct: Why should B be in phase with E? I thought the B field exists only for the stationary observer who feels the E field changing. The maximum rate of E field decay is felt by the observer when the slope of the E "wave" is steepest, ie when the wave cuts the x-axis; Am I right? So, at E=0, the B _should_ be Max. Therefore, E and B _should_ be 90° out of phase. Why do all textbooks show them in phase? What am I missing?
Robotix Sir I have one don't if an accelerated charge produces electromagnetic field, we can see the power transmission lines carries accelerated currents then in that case the electromagnetic waves should travel long distances and induce current in all the conducting material around that lines should induce current like as EM waves from antena induces in receiver antena. Please clear this dout
@Electrical Disturbance re:"Antenna is reactive part of system , and all science story is wrong. Is impossible to have max value E and B field at same time" . I will submit, ED, that the folks who researched direction finders in the 1920's onward have some idea about the E and B field phase relationship. I suggest you check out "Direction and Position Finding by Wireless" written by Ronald Keen in 1922. Here is an online source: archive.org/stream/directionandpos00keengoog#page/n6/mode/2up
The fact that you take the time to do these videos and share them reflects the great character you must have! God bless you sir!
This guy makes physics so much fun! :""D
I laugh while learning, that's a plus.
You know what surprises me more about you is the time you take to share to all of us orphans of mother science !
One thousand thanks !
Marcos Rivas That's a nice turn of phrase! You're welcome!
i wish all my professors sounds as enthusiastic as you, it helps a lot listening through the whole thing. And great content! Thank you!
Resonance. I have a video on it. Get ready to fall in love with the universe all over again.
Thanks for the props, too!
👁⭕👁
Probably the most entertaining video I have seen in months! Thanks for creating this, now I understand :)
YOU'RE WHAT'S RIGHT IN THE WORLD! I never thought I would laugh and actually enjoy learning physics. THANK YOU
ME TOO!! I NEVER LIKED PHYSICS,BUT THIS GUY NAILED IT!HE SOUNDS LIKE RYAN REYNOLDS IN DEADPOOL HAHHAHAHHAHA
4:44 "Strange because of diarrhea" Like wuuuut Scoob!!!! Lol
@7:30 "This pissed me off a little bit."
Sums up how I feel about everything I've learned in physics thus far.
your cool way of deliver plus the information within makes this an informative and relaxing video.
I have pumped almost every video out there to properly understand how propagation works , by far this is the best explanation ever !
It always bothered me as a student that how it physically happens and your video helped me understand that. Thanks a ton sir, your fun way of teaching makes learning a fun experience :)
This is how i imagine Scott lang teaches physics to Cassie😊 you're amazing
Simple and entertaining, just as school should be. Man, must it be so tiring to entertain while lecturing! Thank you, you earned a subscriber
This is the best explanation of electromagnetic waves I've found on youtube. THANK YOU VERY MUCH!!
OMG, you explain this so well that I even got emotional after watching this. THANK YOU so much!
Incredible video......I have been in radio communications my entire work life, and that's the best explanation of RF propagation I have ever seen! Great job, keep them coming! There's a lot more I need to know!!!!
His reasoning is incorrect.
@@amirq25ify omg don’t say that! I’d hate for all those billions of radios around the world to suddenly stop working!
I suppose so. And you're right - it's hard to imagine a source that doesn't have ANY linear portion at the output. But maybe it's a shielded cable where the signal is coaxial with the ground...
Either way, no antenna means extremely inefficient broadcast. This leads us back to an impedance matching discussion. Fun!
I was so surprised when you mentioned Slovakia. I live there and sometimes it seems like it's a place forgotten by the world. It made my day. Keep the great work up!
+Tomi Adamec Oh, what a horrible feeling! Happy to help!
Dude...or should I say sir, your explanation is the best on youtube...you were able to deliver this boring topic coming up in my test using humor(grade8), intelligence and most importantly..with absolute simplicity....cheers! Many thanks..like
I LOVE this explanation of electromagnetic waves. It uses my previous knowledge of the right-hand rule to intuitively explain how EM waves are created and propagated, which is very interesting! Thank you so much.
I knew all this already (more or less) but you still deserve a like for the presentation. Well done. Never lose the energy you have.
Great video.
Greetings from Slovakia!
Are you on the West side?
Finally I have found true explanation of those sinusoids. No YT channel pay attenention to question fwom where they getting from. But now I got it. Thanks a lot :-)
Awesome. I am so happy you are doing this! My students are going to love this when I tech EM next fall. Thanks.
Your videos are awesome! i enjoy learning physics from your videos because my professor is so BORING and I get nothing out of him. honestly I've learned more in a day from your videos than I do in a month from the class I paid for...I have an exam coming up so expect to see a boost in views lol!
Saying hello from the great country of Slovakia.
+Šimon Šimonn My son just said, "SLOVAKIA!!!" Yay!
What's something like great in Slovakia.. it's not ex ussr state
@@jitendranihaliya5677 former yugoslav however
@@tord1508 So what yogaslavia was not great empire ..
learning EM waves has never been so exciting..Good explanation full of coherence and humor. THANK YOU
At 4:15 there wouldn't be a "big"-"small" electric field generated, but a "big"-"small"-"big" as the wave propagates - the electric field below the x-axis isn't small just in another direction!
For years....I have tried to understand EMW. This video creates that understanding.
I'm so happy to hear that! Thank you!
"At the same time we've got, essentially, a current in this wire. Now thats a little bit strange because of diarrhea." HAHAHA great explanations btw, I'm a Chemistry major currently in Medical school and stumbled on your video. You really know your stuff! Thanks for posting :)
Let me just say that you earned my respect. It seams as your words are always trying to keep up with your brain. but you think very fast, so you speak very fast. But I must say again: you have my respect. Please, keep making videos like these. "Thinking mankind" thanks you!
Let me propose a question: could I shift a visible light frequency to an invisible one (and vice-versa)? For example: can I turn visible light to UV light?
Thanks! Shifting light would mean absorption and re-emission. As long as energy is conserved, you can surely do that. Visible to UV is an increase in energy for each photon, so you'd have to have something feeding the beast, as it were. If you look up how fluorescent lights work, you'll see that shifting frequencies down is not only possible, but quite commonplace.
Doc Schuster Or you've got to be really far away and the light source has to be pulsating and moving towards/away from you fast enough for a Doppler Shift into the invisible.
*****
Brilliant! That's a much better answer than mine! Not a convenient procedure for the lab, but quite commonplace in the universe.
A very cool video. I love your (slightly mental) delivery
I love how enthusiastic you are!
...yes. You are entirely correct. However, at low speeds, this radiation is very small. But think about the cloud chamber tracks that you've seen - they all curve in.
AWESOME. makes me want to spend my life getting to know all this weird stuff.
Great question. Their amplitude is in strength of field. Only waves that have physical media have an amplitude that can be measured in distance. Nice work!
i m from programing field, but developed interest in this... ur videos r super cool.. subscribed.
datz a mindblowing explanation! wow! have been always wondering about em waves but never got it ryt.
indeed this video deserves more views.
Your explanation is RAD! keep up the good work
The best explanation ever, happy to discover your channel. Job well executed
Thank you for making these videos for us; they're tremendously helpful for university physics!
Im from Slovakia and you made my day with this one :)
Yep. Synchrotron Radiation. We typically don't mention it in the first year classes, though.
This is a beautiful explanation! I've struggled with understanding Maxwell's Equations on an intuitive level for what feels like forever, and now I finally feel a bit confident on the topic. Thank you so much!
I'm so happy to hear it. I'm sure when I get to synchrotron radiation, you'll be well beyond that, as well. Maybe YOU should make the video... Keep learning!
Best lesson I've ever learned in my life, I feel like a kid again.
I love your enthusiasm!!!!! THANKS>> I LEARNT ALOT!!!!
Dude, this is so well presented
This is great. I wasn't planning on watching a video on Antennas but it randomly autoplayed and well.. not disappointed in the least. Love your enthusiasm and eccentric speaking style while explaining the topic. Kinda of hilarious while informative. *thumbs up and shit*
Holy shit! You just made me understand how antennas work! Thank you sir!
Great explanation for such great concept! I used to draw that E/B propagation wave when I was at uni, as I was a shortwave fan (dixer) it made sense to me and I got it right so far. but here the UNLOCKING piece was the timeline and and the Electric field move while a new one is generated at the source. that explains why a source cannot be a constant electric generator, unless you want a single pulse at the switch-on/off step. Brilliant! new subscriber indeed!
Best explanation!
Love from India. .❤❤❤😊
Thanks for letting me know, Tom! You're welcome. Keep up the hard work.
The transmitter antenna seems to be tuning fork transmitting its vibrations to the other tuning fork/antenna.
Light travels at a rate of induction through the aether. Aether transfers vibrations of light like tuning forks.
There is no aether! That is the key result yielded by the Michelson-Morley experiment. Electromagnetic radiation seems to propagate as a wave, but interacts with matter as a particle. Refer to Young's double slit experiment and Einstein's explanation of the photoelectric effect.
Classical Physics breaks down in the realm of the very small and the realm of the very large.
Wow. Never saw a light radio explained so well ;)
YAAAAS thank you so much for this, I've always been kind of not okay with EM waves, because like what's moving? What's making a wave? and now I know.
The magnetic field goes around the antenna experimentally. The sideways pointing magnetic field atrocity probably started in 1888 by Oliver Heaviside.
I regret that I'd have to look up those topics myself in order to make a video. I'm presently focused on making a solid first-year university physics curriculum. Good luck, though. Those are fun topics.
Is there be not an antenna which can convert light radiation into electric current?
Best explanation ever! Even after 10 years and watching numerous videos, I finally understood. Thanks :)... I have a doubt: because an antenna uses AC current, the magnetic field propagates through space. That means if I use DC, its field stays around it and doesn't propagate, similar to a permanent magnet??
That's how the freaking physics is taught! Wow! You're a genius!
subscribed.... You sir are a rockstar. you love this stuff and I appreciate the time that you put in this small video. your manner of teaching has cleared up years of confusion in just under 15 minutes. absolutely lovely!
Just for some channel input, I subbed at "tHiS iS a RaaAaAdioOoo" @ 11:22 lol
I LOVE your energy! This has been so fun
Great video. Thank you for actually spelling out how these systems interact with each other, and explaining the physics behind it. A lot of videos on signals are either wayy too specific or wayy to general.
Wow it's impressive what a focused mind can do. I think you must have a good grasp of things I'm just learning. I don't know enough about these things yet but I think it's about the pictures I took recently....you might like my latest video.
Insane teacher... Really enjoyed!!
I loved every second of that! DANG
So that's how the EM wave is produced and propagates! Many thanks
Great! Great! Awesome explanation! Thanks!
I enjoyed it, one of the best I've seen.
Great presentation!
For this exact concept you are a different person tomorrow as you were today
Thanks! And to answer 3...it seems like it should. But then...why don't we have wire/antenna visible light sources?!? I'll have to think more about it. Excellent question. Anyone else care to lend a thought?
The way you explain Doc
Dang
Just awesome
Love you👏👏👏👏👏
Awesome explanation! Thank you.
I also once harbored that misconception, friend. The B and E fields are actually in phase for all traveling E&M waves. Weird, huh?
The math explaining why is beyond a college freshman level, but I may make a video on it someday.
Your video is always fun to watch :)
Many thanks for the very interesting and fun way of explaining EM waves. DANG!
Thanks! Your channel looks great, too. I did a fair amount of proton NMR for my thesis.
this is actually amazing thank you so much
5:40 I thought that current is going from positive to negative by convention. So it would also be in the direction of the electric field....How come its opposite on your drawing?
Ahh, that's because electromagnetic force travels the path of leas resistance. You are correct both flow from positive to negative but electromagnetic force travels in a circular motion. The fact that he drew the lines in an opposite direction seems to be what threw you off. Imagine a coil being wrapped up alongside the current flowing in a straight direction, that might make more sense. You can visualize the flow by drawing ang an imaginary line through the arrows left to right. The imaginary coil (EMF) is indeed flowing left to right. Draw a coil so you can physically see the directions going up, down, left, right creating a circular motion.
@@rodrigogomez5035 Are you saying he drew the arrow in the wrong direction? Also, what is electromagnetic force? Did you mean to say that electromagnetic _waves_ travel in a circular direction?
You forgot the detector before your amplifier on your "radio" receiver!...But I like your enthusiasm.
A nice explanation indeed!.. Keep it up.
Man you have talent!! thanks this helps me a lot!
Almost none of this is my own insight, but I'm really happy that my style is helpful for you! Keep rocking!
Well, the presentation was nice but I have two doubts: -
1) You say that the current is maximum when the electric field is maximum. But, we know that in simple harmonic motion, the velocity is maximum at the mean position. Thus, when the charges are maximum (and we have maximum electric field), they should produce no current. Hence, the rate of flow (velocity) of charges i.e. current should be maximum when electric field tends to zero. Hence, maximum magnetic field should be observed when electric field tends to zero as the magnitude of the magnetic field depends on the velocity of charge.
2) I did not understand why the electric field should move forward...
Gramercy...
very nice lecture.. very well explained. Congratulations
love your explanations you make it so simple and so appealing !
Very interesting way of teaching. Congrats professor.
super!...Just one little thing.......from about 4.20 to 4.25 you refer to "big electric field to small electric field to big electric field........" ....this of course should be from large electric field in one direction to zero then big electric field in other direction then to zero......." (A trough of a wave is not a minimum, it's a maximum in other direction. But, apart from that, what a fantastic explanation with great diagrams you have given.
BEST VIDEO ON UA-cam FOR SIMPLE EXPLAINATION OF WAVES!!!
I'm still puzzled about one thing- Why does the frequency of the recieving antenna HAVE to be the same as the frequency of the propogating antenna? Please don't tell me its just the laws of nature (I'd appreciate a detailed explaination). Thank you in advance
Amazing video, a million thanks. Can someone please explain though, why the electric field moves through space in the first place? Why it displaces along the paper
Another terrific video, thanks!
Sweet explanation. I get it now. Thanks for posting
Wow thank you very much. I have been wondered about this for soooo long!!!
Doc yoi rock! Man you were pissed off of that em wave graph touching the axis of propagation again and again. I heard you saying that in some other video of yours and I got pissed too. And today you have solved my problem. Now I know why it touches the axis of propagation. Thanks to you man. You both ruined and made my day. Really cool! ;-)
good explanation Sir👍
yay, you used slovakia :) btw love your videos, they really help with things i only kind of understood in highschool and need to understand fully now
I'm glad to hear it! It's easy to be enthusiastic with such great students.