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EM waves in *Real* life

  1. Mar 13, 2015 #1
    hi, everyone I didn't know where to post this thread so I posted it here. I have read many articles about EM wave to find what I'm searching for and nothing still. I have seen many pictures, animations and videos about EM wave, and about oscillating charge, but still nothing. What I am really curious about is why there is no animation or picture about Electric and Magnetic field together from the point of an oscillating charge, but there is only electric field shown. e.g.

    rad_vis1.gif

    Basically I need something like this
    MagneticField_2.gif
    but as first two pictures (I mean when it's oscillating).

    So another question follows, is electromagnetic wave really how it looks like in many pictures and animations? e.g.
    EMWave.JPG
     
    Last edited by a moderator: Apr 19, 2017
  2. jcsd
  3. Mar 13, 2015 #2

    mfb

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    2016 Award

    Staff: Mentor

    Graphing both components of the electromagnetic field in 3 D sounds like a real mess. Shouldn't be too hard to compute how it would look like.
    If you extend that single line to cover all space to get a planar wave, it is not completely unrealistic.
     
  4. Mar 15, 2015 #3
    I'm getting hard to understand electromagnetism, I'm a rookie, and I'm not so good in physics, as you can see, so I'm sorry if I'm asking pointless question. well the last picture I posted shows the fields far from the charge, what I want to know is how is it formed, no problem for electric part of the wave ( I figured that out from first two pictures) but magnetic part concerns me. That's why I'm asking for a picture or an animation of an electric and magnetic fields together from the point of an oscillating charge, to make conection. Let me show you what a rookie I am.

    chargeMoving_2_20090117113837.gif

    please stranger I beg you if you can help me with this one, because time has come to decide should I continue understanding physics in my very own way (like detective Columbo solves his cases), well that's I think the easiest way, or should I stop with that for good. and thank you for your time and answare
     
  5. Mar 15, 2015 #4
    I can't help you with your specific request of EM waves visualization. The fact is that didactic resources run thinner as you get deeper in any field, so if you want to learn these stuff by yourself be aware that there is no shortcut, you have to have patience and will power to go through the usual road: textbooks.Very often I find myself struggling with a difficult concept that would be immediately clear with a simple illustration, but it's only described in a couple of books and one of them is poorly translated from German.
     
  6. Mar 15, 2015 #5
    thanks man, I needed this, I needed someone to tell me that in a simple honest way
     
  7. Mar 15, 2015 #6
    The further you get into physics, the harder it will be to find good animations. There are a number of reasons I see for this.
    1) As mfb mentioned, it's really hard to come up with a good way to visualize complicated systems. Electromagnetic fields are tough to visualize, because you're trying to turn two different 3D vectors in 3D space into a single 2D set of colors. You're going to lose a lot of information no matter what you do, so figuring out how to show the best set of information can be very challenging.
    2) These animations usually take a lot of time to make: even the "simple" ones. People will tend to focus on animations for core concepts rather than specific problems. For example, I could probably make an animation exactly like what you want, but I know that it would take quite a lot of time and effort on my part. I really don't think it would be worth it.

    My point is, even if there is an animation for this specific problem, it won't be long before you come across a problem with no good animation.

    Now, the question is, what do physics/engineering majors use when they don't have an animation? Most of the time, the answer is a lot of math and a lot of imagination. Worst case, they build their own simulations/animations (which takes a LOT of time). I don't want to discourage you, because it's great that you're interested in this stuff. However, it really does take a lot of work to wrap your head around problems like this. If someone hasn't done the work for you by making a nice animation, you're pretty much stuck doing it yourself.

    To really understand this specific problem, you would probably need to do a full-blown year-long course on electricity and magnetism, using a book like "Introduction to Electrodynamics" by David Griffiths. You would learn about Maxwell's equations, which pretty much describe all electromagnetic fields/waves, and you would use those equations to solve for the fields of a moving point charge. Unfortunately, before you do all that, you'll definitely need to do some courses in vector calculus and differential equations.

    I would encourage you to study physics "properly" (i.e., learn all the math) since you seem so interested in it. It can seem unachievable when you look at the mountain of topics you have to learn, but if you're interested in it, the climb is really a lot of fun. It takes a lot longer, but you'll get a lot more out of doing things the hard way than you will out of relying on animations that others have made.

    Take a look at this website, written by a Nobel Prize winner: http://www.staff.science.uu.nl/~gadda001/goodtheorist/classmech.html He gives a pretty good outline of the path you would take to learn physics properly.
     
  8. Mar 15, 2015 #7
    You are great, thank you for your time. You really encouraged me, you gave me a pretty good answer and insight in all that. Now, about calculus and differential equations I have basic knowledge. I just finished high school and was planing to study physics, but I'm more interested in nanoengineering, field - nanorobotics. But because we aren't developed in a field of nanorobotics and because in my country there are no universities about nanorobotics I have no idea what should I chose. I thought maybe I should chose physics in atomic level. Studying engeenering, mechatronics, robotics doesn't seem that will fulfill my needs, if I may say so. So that's why I decided to study physics in atomic level with taking some courses of nanorobotics (of course don't have to be in my country), and going through some books. That's all I could think of. Also I am interested in electromagnetism, as you can see. S**t, I love physics, all branches, but my knowledge sucks. Any advice about all that? Well, for the last two sentences you don't have to, you already gave me.
     
    Last edited: Mar 15, 2015
  9. Mar 15, 2015 #8
    Why not study something like electrical engineering, maybe with a minor or double-major with physics? As far as I know, most people who end up in Nanotechnology don't actually have a degree in "Nanotechnology." They'll have a degree in electrical engineering, mechanical engineering, physics, or chemistry, for example. Nanotechnology is a fairly new field, and most universities don't offer a degree in it specifically. I'm actually going to be starting a Master's in Nanotechnology soon, and I'm coming from electrical engineering with a minor in physics. If you do a degree in something similar and keep your grades up, you should be able to pursue nanorobotics at a graduate level.

    If you want to really learn this stuff, the best way is to get a university degree. It's theoretically possible to get the same level of education just by self-teaching, but I don't personally know of anyone who's done it. It would be extremely difficult to do effectively.
     
  10. Mar 15, 2015 #9
    So you are saying that studying physics, mechanical engineering, mechatronics or robotics is fine for my purpose?
     
    Last edited: Mar 15, 2015
  11. Mar 15, 2015 #10
    Yep! As I understand, nanorobotics is something you would usually specialize in after doing a more general degree like physics or engineering.

    If possible, find a university which does research in nanorobotics, but it's not the end of the world if you don't. Like I said, I'm doing my undergrad in electrical engineering and physics. My school does almost nothing in the area of nanotechnology, and yet I had no trouble getting into a Master's program in nanotechnology at a different university. If you can find an undergraduate program in nanotechnology that's great, but it's really not necessary.

    The big thing is to get started in the right direction with a general degree like physics or engineering, and then you can specialize as you go along. Regardless of what flavour of physics/engineering/nanotechnology you take, you'll probably find that a lot of your courses for the first few years will be pretty much the same anyway (fundamental math, physics, chemistry, etc.). So you'll have time to figure out exactly what path you want to take.
     
  12. Mar 16, 2015 #11
    My man, thanks a lot
     
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