A plane electromagnetic wave is traveling vertically downward with its magnetic field pointing northward. Its electric field must be pointing either towards the south, east, west, or vertically upward. The speed of propagation of electromagnetic waves in free space is exactly the speed of light, and the relative magnitude of the electric and magnetic fields in an electromagnetic plane wave is determined by Maxwell’s equations.
In a vacuum, electromagnetic signals propagate at the speed of light, making it difficult to create a plane electromagnetic wave. Chapter 9 discusses the propagation of plane waves in vacuum and simple media, at planar boundaries, and combinations confined between sets of planar boundaries. Two simple types of incident electromagnetic waves can be superimposed to yield any incident wave polarization: transverse electric waves (TE waves) are linearly polarized.
A plane wave travels in the positive z direction in a conductor with real conductivity. The electric field of an electromagnetic wave is perpendicular to the magnetic field, and both are perpendicular to the direction of wave propagation. Therefore, since the magnetic field is pointing eastward, the electric field must be pointing vertically downward.
The direction of propagation of an electromagnetic wave is perpendicular to both electric field vector and magnetic field vector. For a plane electromagnetic wave traveling vertically upwards, with a magnetic field towards the west, the direction of the electric field must be towards the North. In summary, understanding the propagation of electromagnetic waves is crucial for understanding their properties and applications.
📹 Electromagnetic Waves
Why are the Electric and Magnetic fields in phase in an Electromagnetic Wave? My Patreon page is at …
What direction does EMF go?
The electromotive force (EMF) is defined as a force that acts in a negative direction within a circuit. This force is generated by a current that drives the movement of electrons around the circuit, which in turn produces a change in magnetic flux.
What direction does emf flow?
In an experimental context, the electromotive force (EMF) in an electric circuit is consistently observed to act in a negative direction. This implies that the current generated by the EMF opposes the change in magnetic flux, which is responsible for producing the EMF.
What happens when a wire in the Earth’s magnetic field carries a current vertically downward?
A neutral point can be achieved when a wire in the Earth’s magnetic field carries a current in a vertical downward direction.
In what direction is an electromagnetic wave traveling?
The correct expression for the magnetic field vector of an electromagnetic wave traveling in the x-direction is given by Ey=EAsin(kx=ωt)J, where c is the speed of light.
Which way do electromagnetic waves travel?
Electromagnetic waves propagate in a straight line in the direction of their propagation, undergoing directional changes when they interact with an object. As an illustration, visible light can be regarded as a case in point, insofar as the photons that constitute the wavefront are subject to scattering when they encounter air molecules.
Do electromagnetic waves travel in the same direction?
Electromagnetic waves are a form of electromagnetic radiation that propagates in a straight line in the direction of emission, undergoing directional changes upon interaction with an object.
What happens when the wire is moved down through the magnetic field?
This interactive teacher demonstration demonstrates the concept of inducing an electrical potential difference by moving a wire through a magnetic field. The demonstration uses a sensitive ammeter, a 2 m length of wire, and a strong horseshoe magnet. It introduces students to the essential ideas of electromagnetic induction, which involves a new way of thinking and talking. The physics explanation involves conductors cutting magnetic lines of force, so care must be taken in presenting these ideas. Emphasizing the importance of this seemingly simple effect is crucial as it forms the basis of all electrical supply worldwide.
What happens when current in a wire is flowing in the vertically downward and magnetic field is applied from west to east?
In accordance with Fleming’s left-hand rule, the force exerted on the wire will be attributed to the south.
Do electromagnetic waves travel up and down?
Electromagnetic (EM) waves are defined as electric and magnetic fields that change over time and position. This definition is analogous to that of waves on a lake, which also change over time and position. When a charge is situated in the trajectory of an electromagnetic (EM) wave, it exhibits a vertical and horizontal movement due to the influence of electric forces. It is not necessarily the case that the electron on the antenna follows the sine wave representing the electric field. Rather, its position along the antenna is determined by its initial position and acceleration over time.
Can waves only travel up and down?
Waves propagate in various ways, with body waves being the most significant. P-waves, also known as longitudinal waves and transverse waves, travel like a spring being pushed back and forth, while S-waves travel up and down like a rope attached to a wall being jerked up and down. Wavelength is the distance between two crests or compressions of a wave, while amplitude is the maximum displacement from the stationary position. The velocity of a wave is measured in meters/second and is equal to the frequency times wavelength.
P-waves, also known as pressure or push-pull waves, compress and change the shape and size of an object when moving through it. S-waves, on the other hand, act like a rope attached to a wall and only change the shape of the object when moving through it. Both waves decay over volume.
What direction is the electromagnetic wave moving?
The propagation of electromagnetic waves is typically perpendicular to the plane in which the electric and magnetic fields lie.
📹 The origin of Electromagnetic waves, and why they behave as they do
What is an electromagnetic wave? How does it appear? And how does it interact with matter? The answer to all these questions in …
6:01 it is worth noting that some animals can actually see light polarisation, eg. some insects recognise polarised light and use this ability to detect pools of water (its surface reflects light with horizontal polarization more strongly than with vertical polarisation), kinda like they were wearing polarised sunglasses. Fun fact is that even some humans have very limited ability to see polarisation – look for “Haidinger’s brush”.
Wow! I am 50 years of age now and from the age I went to, what was called Middle Technical School or MTS here) I had majors in Chemistry, electrical engineering / technology, physics, mathematics and all. Every major educated their own little part of the whole story and up till now I haven’t seen a combined basic explanation like this which should be the basis of all above mentioned majors! Why, because your article literally gives a concrete understanding about the foundation of all that’s teached and how all the bits you learn is actually just one basic fact about particles, matter, how this behaves and what follows as a consequence out of this fundamental behavior. In my quest to such an explanation as I wanted to now exactly this, people only repeated what was said in school or evade an answer by saying that it is to complicated to explain. And here you are (!) doing it in twelve and a half minutes! This basis shows also what I already thought for years and just recently showcased by the wonderful youtube website Veritasium by Derek Muller. That, in electrical current, it’s actually the electric-magnetic waves that carry the energy and not the flow of electrons, because electrons hardly flow anywhere! They just pass on the electric energy to their neighbor and the electro-magnetic field which they create through the excitation brings the energy over to the other side. That’s why the material of the wire, their width, wheter it’s a bigger solid core or separate strands and isolation can make a huge difference in how that current or signal is distorted or not.
Thank god I found this website. And of course you for making these articles. I had accepted for a long time that EMW are something that can’t be really explained rather we only observe them. But I have a hard time to really be fascinated without a clear explanation of the HOW and WHY. That is why I LOVE physics. It’s the world view that is changed.
For those who want a quantum explanation of the phenomenon: Elettromagnetical waves are nothing more than quantized photons who propagate through schok waves (scattering) in the cosmos. The more density of particles there is in a specific zone, the quicker it will expand, like with water, where sound propagates faster because of this reason, being far more dense than air. Photons are known to have a double nature, being both a wave and a quntum particale. This is also the reason why photons still have an impact on particles with mass despite having none themselves. It’s because they’re also waves and, through their pression on other particles, allow them to still impact physically other particles but not be impacted themselves since physical interaction happens because of the exchanged mass between the objects.
2:37 Awesome! I have never understood the source of thermal radiation or incandescence before. Everyone always talks about luminescence and the source of those photons, that’s easy to find. I just have never been able to find much information about the source of photons from Incandescence. Looked all over Reddit, YouTube, Wikipedia and there’s literally only a sentence about it on Wikipedia, I checked the articles for Thermal Radiation, Electromagnetic radiation, Black Body radiation, Incandescence, and the only thing it says about it is “The kinetic interactions among matter particles result in charge acceleration and dipole oscillation.” which didn’t seem helpful at all. Those articles are all huge, I can’t believe they didn’t say anything else. It seems pretty obvious now. Thank you!
Oscar Shu 0 seconds ago I work as an EE engineer for a decade, I thought I knew electromagnetic wave well in my daily work, but I still learn so much in this article, really like the explanation for diffraction, reflection, refraction from the perspective of atoms and how light wave slows down in material but the speed of light did not change.
Fun fact: typical 3D glasses DO NOT use linear polarization (mostly because tilting your head would start bleeding in the wrong image for an eye into the right one) but circular polarization (which is immune to this issue); but this can play merry hell with the heads of folks who are only used to how good old linear polarization (think LCD screen foils) works, as in two filters 90 degrees to each other = opaque, rotate one of them another 90 degrees = transparent.
These articles are absolutely fantastic! I could honestly listen to and watch a ScienceClic article about this for hours… I’m always introduced to things through these articles that I had no idea about. I learned the basic information, like reflection and refraction, but I never learned about their inner workings. And some things, like why the sky is blue, have been answered elsewhere, but this explanation is still unique and gets more into the physics behind it. (I would have liked to have seen info about red sunsets as well… Maybe in a future article…) The worst parts about your articles are when you say things like “Finally” or “To sum up”. I just don’t want them to end so soon!
I’ve read 10+ textbooks of physics for optics. And no book had the reason of why in first place the reflection happens. Books show the rays of light bouncing like a ball, I used to feel so ridiculous by that cringy explanations and I’m really thankful to have this website and articles like these! The reason of slowing down of light, oh man it’s eye opening 🙂
My god the animations and explanations are incredibly intuitive! I still don’t understand half of this, but this article answered my old question of “why EXACTLY does light slow down in water” – something that neither my physics teacher of YouTube articles could explain. Man the person who writes these scripts REALLY knows their stuff! This is better than Veritasium or Minute Physics or whatever.
See, I came into this knowing the information already, but I never hear any other science communicators articulate the actual fundamentals like what’s done here, that light is just an oscillation between an electric field and a magnetic field repeatedly inducing one another. The part taken for granted is just that a change in a magnetic field creates an electric field & vice versa, which is already a deeper level of understanding than you typically get from a article about light, even though drawing the connection between electric/magnetic flux and light waves really is that simple. It almost makes me wonder if it’s even that widely understood, but you certainly do, and it’s communicated so wonderfully effectively.
I bet there’s hardly anything else in the Universe apart from electromagnetic waves and all of its various modes of vibration we call particles. I even have a suspicion that gravity is somehow fundamentally linked with electromagnetism in so far as to say it maybe some special mode of electromagnetic vibration that we tend to perceive as a space-time curvature. It’s pure speculation on my part but those articles for sure keep my brain running – such an underrated website.
What a perfect class of electromagnetic waves and light behaviour 👏👏👏. Nothing is redundant or repeated too often… I’m really blown away by the amount of content, the clarity and simplicity of ideas, this is at least has to be coming from some or various people with a PHD in Physics ⚛, and I would adventure to say at the top of their respective classes 😁👏👏👏👌👌
I think for intuition, you should mention that we can “detect” infrared waves by feeling the waves interacting with the matter of our own body. So essentially you can feel the heat/waves. Put your hand close to a toaster, the heat is = IR radiation. I know the website knows. But I think people trying to learn will have great benefit from this intuition.
I’m in my 50’s. I studied IT but also studied numeric analysis and some higher mathematics. One of my friends (mathematician) went through Special and General Relativity with me. I understood some of it but never understood it properly. Thanks to Alessandro Roussel, now I do. You’re an awesome scientist, mentor, teacher and human being. 🥰 I just want you to know that. Your website is BY FAR the best explanation of difficult scientific concepts I have ever come across. Your website should be compulsory viewing for all Physics students in the UK.
Great article. I really like the Clifford algebra story of electromagnetism, where the E field is space-time bivectors and the M field is space-space bivectors, and you can easily derive how relativistic boosts will convert one person’s electricity into another person’s magnetism and vice versa. IMO the magnetic field should be drawn with little spinning disks instead of vectors for this reason (drawing the bivector, not the normal, which is a 3-dimensional coincidence.)
Good teaching is when the student is assumed to know nothing, and is taught clearly step by step with quality analogies and/or many practical examples. A rare art. This is insanely great teaching. First time seeing this content, and I’ve only witnessed such teaching on mathtutordvd til now. Now there are two. Illumination occurs with electomagnetic radiation. This article was illuminating indeed. Subscribed. Illumination through space goes on infinitely, and as such, you are infinitely appreciated. P.S. If this website – without sacrificing this didactic quality that is a lost art – also offered academic training in the most practical concepts like algebra, trig, calculus, differential equations, linear algebra, physics, software, etc. (topics like mathtutordvd covers), It will definitively have made (along with mathtutordvd) universal college education obsolete, ivy league or otherwise. This is not an overstatement. It is fact…
I had to have radiation treatment for a vigourous skin cancer on my scalp. While doing so i intermittently say blue ‘flashes’ while my eyes were closed and asked the radiologist why that was. They could not say exactly. After hearing you mention Cherenkov radiation and never hearing of it i asked Google and discovered that an English team at a cancer hospital had discovered Cherenkov radiation producing light in the vitreous humour of patients eyeballs who were undergoing radiation treatment! Next time i go for my checkup i can give them this info – thanks to you. 🙂 Great job, keep up the good work. If you are able to post a article about electro-magnetic resonance and how it can be utilised for energy production i’d be very grateful.
just to add to article.. particles we talk about are waves, and waves are particles, as they deliver energy in distinct packets.. Frequency of wave changes delivered energy, where shorter waves are more energetic (they transfer more energy to particle they hit), while for lower frequencies you need more mass to absorb energy, so they can easily pass trough matter. Adding energy to atoms makes them more energetic (their kinetic speed increases) and thats what we feel as heat when they form molecules.. they jiggle around more vividly and absorbing that jiggle is what heat transfer is.. also PV=nRT .. adding energy to particle not only increases heat in closed system, but also pressure (as there is more and stronger bounces on walls of closed system).. increasing volume lowers temp, as atom itself doesn’t have any temperature. Water absorbs microwave energy really well, that is why that frequency of waves heat us most, and higher energy waves just kick out electrons from atoms.. Atoms w/o electron is more reactive, can lose bond with other atom by that kicked electron, that’s why radioactive energy harm us, same goes for free electrons from food or other things. When it comes to interference topic, different energy waves travel at different speeds and not only light, that’s how prism effect works. Also atmosphere has a (strong) color, it absorbs green and blue, so it is orange (yeah rly).. that’s why you see red moon or red sunset/sunrise, and why sun is orange from our POV! (while indeed the sun is just white – thats how you would see it when you would be in space (tho surface temperature dictate color, and 6000K of sun would be nice white light) – you can see sun color on full moon, as it only reflect light without thermal radiation (as moon surface is cold) Also I would like to know how reflection works on non conductive materials from this article.
I had some questions which maybe you could address in a future article: 1. You said that when a charged particle moves, it produces both electric and magnetic waves, but didn’t mention why it has to be particularly accelerated, because I had studied in high school that moving charges produces only magnetic field when at a constant velocity, and accelerated charges produce em waves. 2. Why does it actually bend during refraction? I slows down because the field interact with the atoms inside it, but why bend? I mean what is the mathematical equation behind it. Huygen’s principle can explain it but it doesn’t explain from the perspective of the atoms. I have an engineering degree but didn’t study physics after school, so I watch these articles, and would like to thank you for the quality content you put out here.
Actually, human eyes is sensitive to linear polarisation, albeit very little. IPS monitors work by rotating polarization direction, which changes pixel brightness against a fixed plane polarization filter. When screen is fully white, the polarization of electrically controlled variable angle in-plane per-pixel polariser and the fixed filter coincide, so the pixel brightness is maximal. You can see it if you look at an IPS screen in polarised sunglasses and rotate your head—the screen will become fully dark in a specific orientation (horizontal, vertical, or 45⁰, depending on a particular panel). When looking at the fully white IPS panel, some people see a hard to describe effect (I do see it, and I believe everyone can, it’s just hard to notice): I see a very slight vertical bluishness and horizontal yellowishness (may be vice versa, or diagonal; depends on a panel). It’s not lines or something, it’s kinda direction-related tint. I can’t find better words, “bluishness in one direction and yellowishness in a perpendicular direction” sounds weird, but once you see it, you’ll notice. It’s like a tinted cross at the focus of your vision, with each line going wider in the away from your focus point direction; it’s kinda shimmering, more prominent when your sight wanders a bit. Look at the very center, but do not fix eyes on the point, let your sight wander around the center of a fully white page, within 1cm or so, and you should notice it. This will not work on AMOLED panels, common in new phones, tablets and notebooks.
I watch all of ScienceClic’s articles. I fell so blessed I live in an age with technologies that allow us to access such wonderful content and with generous and brilliant people like Alessandro, who share their knowledge in a way we can understand it. I have a question on this topic, though. If scattering in atmosphere happens only on the most energetic frequencies, why then the scattered frequency is light blue, and not an even higher frequency, like violet?
Love this website, just answered my own question. Your articles make the viewer think, thank you! -What are electromagnetic forces though, what are they exciting to propagate? Also photons are vibrating too and their speed, the speed of light, is the 1/sqrt(µ*e), so not only were the photons initally excited to move through space “as objects”, they are also oscillating, creating em-waves of their own. How is it possible to even see clear troughs and valleys of those waves if millions and millions of particles are interfering with each other-
This is the first article of yours that I watched. I liked. I subscribed, I’ll watch more tomorrow, but it’s late now, and I already am having trouble processing all of this information. Also, I had no idea that 3D movies worked like that. That’s really cool! You know what? I’m turning on all notifications too. I feel like this website, combined with me doing research on my own time could really teach me a lot.
Very nice visualization of the EM wave propagating outward. You say that the charge generates the field. Then you say that the wave will spread through the EM fields. Things are a little muddled on these points. You might want to do a article on quantum field theory and clarify the nature of the field and its presence throughout spacetime, even if no charge is present. Nice job overall and appreciate the nice visualizations.
1:07 notes a curious hourglass configuration. I’ve seen this figure before in research. As a research clue it is extremely important to know was the hourglass figure (amongst others) for artist conception purposes or is it based on a paper presenting actual mathematical models and data regarding the interaction of magnetic and electromagnetic waves? Where can one find it? GREAT article.
I think the animations need some focus group testing. They are good, and this article is good. Very good in fact. But I feel like it’s about 85% of the way of explaining things clearly. That said, it is probably the best article I have seen on the topic in general, but with some caveats- in the form of questions generated or things not being clear, or things being done a bit too quickly. I can give specific feedback at certain points in the article, if you’d like.
Congratulations. Amazing series. I just finished perusal the last movie and I am delighted with the content and method of presentation. I have a request: could you make in the future a series similar to general gravity, but with the standard model and its Lagrangian? I would be extremely grateful and I look forward to it.
3:31 Richard Feynmann liked to call it jiggling. He was master at explaining complex subjects in simple terms, he was truly a master teacher. 10:33 The cause of refraction is regularly taught incorrectly. I can attest from attending many Physics Teacher’s workshops that I have not seen any teacher who understands the concept. Their favorite explanation is the line of soldiers marching from dry land into sticky mud which is nonsensical if you just think about what they claim is happening.
Come for better fundamentals of physics End up learning Why the Sky is blue, new perspective of the sun being a mass of tiny wibbly magnets and that’s why we can feel heat, and that mirrors have an electric charge of sorts on its surface among other things. Thank you so much for this work you do I truly appreciate it and you, happy holidays
That guitar hero visual where the atom model vibrates and that vibration propagates thru the field clicked it for me. I can start building on the model. I can imagine each photon flying off like a cloudy wave thing of quantum uncertainty but then when you imagine taking a snapshot of it it becomes like one of the arrows pointing in a specific direction. And how the photon is literally just carrying the information that that atom wiggled in this manner at this point in time. And how it’s really all quantum mechanical but we only get to see it in snap shots cause of how we measure stuff.