Understanding Electromagnetic Radiation! | ICT #5

In the modern world, we humans are completely surrounded by electromagnetic radiation. Have you ever thought of the physics behind these travelling electromagnetic waves? Let's explore the physics behind the radiation in this video.

[AdamBechtol]

Can't say I've fully grasped it, but glad this video exists.

[Alex_science]

I am a telecom engineer and this is the most clear and understadable explanation I have seen. Great. Congratulations.

[alexanderquilty]

After watching this the bajillionth time, and 3 years of physics, i’m really starting to grasp this! Thank you for this visual! I don’t know why none of my textbooks ever even discuss kinks and what they would look like!

[karthiksathyanarayanan]

I must say, this brought a smile on my face to see how beautifully you have explained this stuff. Teaching and learning this stuff has always been a challenge for engineers.

[DF-clbm]

This has to be the best explanation I've seen of wave propagation! I actually understood the mechanism by which the propagation of the wave occurs. Well done!

[favesongslist]

I am an ex electronics design engineer and this is the most brilliantly clear, non mathematical, non quantum yet lucid explanation I have had the privilege to watch. Congratulations.

[ddtrahan]

I have an Engr Degree & Master Electrician - this video covered 2 Electrical Engr classes rather quickly! Good luck.

[lordemed]

Hertz was a freakin' genius. He died at age 36, likely from a brain tumor brought on by his experiments....who knows what he would have discovered if he had lived longer

[scottjacobsen]

I design mobile cellular antennas as part of my job. I thought the video was a great depiction, showing the propagating mode(s) as a kink, but I should clarify that antenna designers for cell phones don’t use halfwave dipoles. Rather, we use a random geometry of antenna traces to transfer energy from the board to near fields and hope that in the mess of fields surrounding the cellphone, some form of propagating modes also arise. A little shared secret among antenna engineers is that we don’t have a clue how our antenna actually work as it’s impossible to decompose fields into their constituent components using full wave simulators. We can only look at the aggregate fields. With a dipole, it’s easy to analyze and the modes pop out of the math.

[FahimKhan-vdyp]

you've taught me what my undergrad microwave course failed to teach. thank you! back then, my teacher and fellow students just cared about maths behind these amazing insights. all they cared about exams. i feel sad that this video was not released back then( around 2 years back) . math always gets interesting in engineering when you actually get to know what actually you are calculating. engineering is a beautiful thing to learn and to practice, but, one or two careless teachers- it can sure be hell.

[druryd]

i always knew that electromagnetic waves were kinky.

[JossinJax]

I am stunned at how much I learned in under eight minutes; this pretty much neatly sums up both an intricate and cursory look over all of Uni's second year physics.

[Logan-qinx]

I'm just trying to learn about electromagnetic radiation for an earth science class, this really is an endless rabbithole!

[danielshade]

I would say the greatest acceleration was regarding my lack of understanding of the information presented in this video. I was good for like the first minute or two. By the end I was approaching the speed of light of misunderstanding. My mass also increased, of course, to the understanding that 11 locomotives have.

[Gengh]

The impedance matching mentioned is only correct for purely resistive loads without an imaginary component (provided by reactive components such as capacitors and inductors).
Maximum transference of power is achieved when the load impedance is the conjugate(Z*) of the source impedance(Z).

[MrHichammohsen]

Nice video. Note that the electromagnetic wave does not move in a sinusoidal 2D wave, but in a circular 3D motion that translates into 2D waves when we detect them because we are only measuring on point in space.

[LaughingInfidel]

This level of explanation isn't easy to find. I've wondered about this for years and finally decided to find a real explanation. It took over 2 hours of wading through irrelevant, simple stuff to find this. The idea that accelerating charges create kinks in their fields that propagate out at the speed of light was a real light bulb moment for me. Thank you.

[TheYeeshkul]

Just a few notes :)
Hertz's experiment: It wasn't the spark that transmitted the wave (Edit: the spark itself will / is able to emit an EM wave though). The spark merely triggers the dipole oscillation. He used a massive DC voltage surge released into an oscillator (or without it) and then to a tuned dipole arrangement with a spark gap. The spark fluctuates, behaving also kind of like AC, that's why it worked even without the oscillator. The dipole then produces a dying wave, not a continuous wave. The wave is emitted by the whole dipole, not by the spark in the middle of it. Herz created the first dipole arrangement by pulling a capacitor electrodes far apart (the balls). The emitted wave was received on a loop that really was another LC resonator (L was represented by the loop or square of certain diameter and C was represented by the gap).
6:50 if the impedance of the power source/cables doesn't match the dipole input impedance, the power is reflected right on the transition point between them. This looks like it is reflected on the dipole itself.
I really liked the portion of the video, where you explain how the EM field leaves the conductor.

[satishgoda]

Wow! My impedance mismatch has been corrected by your audio visual signal. Thank you so much.

[Bllctn]

I agree with @DF "This has to be the best explanation I've seen of wave propagation! I actually understood the mechanism by which the propagation of the wave occurs. Well done!"