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Can the light create electromagnetic field?

  1. May 19, 2007 #1
    I will be very happy if you answer me. I tried several times on google to search about this but I didn't find anything. So please answer me, if you know the answer. Thank you.
     
  2. jcsd
  3. May 19, 2007 #2

    Danger

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    Light is an electromagnetic field. It is simply our way of identifying the visible (and near-visible) segment of the EM spectrum. There are several arbitrarily defined segments such as microwave, radio, X-ray, gamma, IR, etc.. Light is generally considered to be the part that we can see.
     
  4. May 19, 2007 #3
    Is it field?
     
  5. May 19, 2007 #4

    Danger

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    This isn't my area, so I can't give you a definitive answer. Essentially, though, yes; it is an electomagnetic field propogated by photons. If I understand it correctly, it is in fact 2 fields. One is electric, the other magnetic, and they travel together but oscillating at 90 degrees to each other. Someone more knowledgeable really has to take over from here.
     
  6. May 19, 2007 #5
    Yes. There is one and only one difference between, say, and EM wave at microwave frequencies and that of a red beam of light is the frequency of the waves. They are exactly the same in physical properties and makeup.

    Pete
     
  7. May 20, 2007 #6

    DaveC426913

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    Well.... two.



    One of them does a lovely job on my bag of Orville Redenbacher's..
     
  8. May 20, 2007 #7

    Danger

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    If the last commercials that I saw were any indictation, the microwaves had far more effect upon Orville's bag than just popping his kernals.
     
  9. May 20, 2007 #8
    If you say that the light is field, then I will make electromagnetic induction with light and get current in closed circular loop.
     
    Last edited: May 20, 2007
  10. May 20, 2007 #9

    ZapperZ

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    And you do! People who work in designing accelerator cavities have to deal with wall currents due to the the changing B fields. That is why you have lossy material.

    Zz.
     
  11. May 20, 2007 #10
    Can you give me some link or picture?
    So let's conclude the light is electric and magnetic field, right?
     
  12. May 20, 2007 #11

    ZapperZ

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    As I have mentioned earlier, please READ and STUDY the Hyperphysics link I gave earlier, especially on electromagnetism. You would not have to "conclude" such a thing if you had spent time doing that.

    Zz.
     
  13. May 20, 2007 #12
    Due to the high frequency of a light wave the light would not be able to penetrate inside a conductor. Same thing with x-rays.

    You wanted a picture, right? Draw a picture of an EM wave and you have by neccesity drawn a picture of light.

    What part of "Light is an EM wave" don't you understand?? Its a pretty simple idea.

    Pete
     
  14. May 20, 2007 #13
    Look man, if you say that the light is both part of magnetic and electric field, then, the photons "are moving" (so the magnetic field is moving), so it will produce current inside the conductor, right?
     
  15. May 20, 2007 #14
    It does produce a current. YES. Light does produce an electric current in any conductor it hits. Indeed.

    But light has a very high frequency. So because the frequency is so high, the "electrons in the conductor can't move fast enough". So the current is very very very very small.

    That's an oversimplification, but I don't know what else to say that will be understood.
     
  16. May 20, 2007 #15
    Why the electrons can't move so fast when the magnetic field of the light is moving so fast? Practically, when you move magnetic field faster, so the electrons in the conductor are moving faster, so the current is stronger.
     
  17. May 20, 2007 #16

    ZapperZ

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    1. The electrons are in a conductor, i.e. a medium. There are other things in their way!

    2. Electrons have MASS. EM field does not.

    Zz.
     
  18. May 20, 2007 #17
    Suppose you are pushing a child in a swing. Let's say you give a push every two seconds, to increase its amplitude. What would happen if you gave a push every tenth of second? The swing wouldn't move much. Make the experiment.
     
  19. May 20, 2007 #18
    I think you have wrong understood it. Look, I made that experiment. So if I push with 0.1sec (with same power) when I will get to 2 sec (0.1*20) so the swing's moving speed will be so fast, 20 times more then once in 2 seconds.
     
  20. May 20, 2007 #19
    It's hard to explain in such simple language. Pick up a spring. Hold it by one end. Move it up and down slowly. Now try moving it faster, and faster, and faster. Eventually the spring won't bounce very much anymore because you're shaking it too fast. It can't keep up.

    Electrons have mass, and they also have other things "holding" them. They are stuck in a "soup" of other electrons, so they can't just move as fast as you want.
     
  21. May 20, 2007 #20
    But man, when you practically moving magnet among conductor, it will induce current inside of the conductor. When you move the magnet very fast so the electrons are moving very fast, right?
     
  22. May 20, 2007 #21

    Mentz114

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    The electric and magnetic field components of light are oscillating very fast. This means they reverse their direction too quickly to move the electrons any distance. The situation has been explained in the earlier posts.

    When an radio antenna picks up a signal, it is responding to the oscillating electric component of an EM wave - essentially low frequency light.
     
  23. May 20, 2007 #22
    You are not moving it "very fast" compared to light. The fields in a light wave oscillate hundreds of trillions of times per second. If you can move your magnet that fast, the electrons will stop keeping up with you.
     
  24. May 21, 2007 #23
    So, when you move the magnet very fast among conductor in closed circular loop you create stronger current. But what will happen if the light wave oscillate hundrets of trilions times per second? The electrons will not move, but why?
     
  25. May 21, 2007 #24

    rbj

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    you're not listening. whether you are generating light (or any other E&M field) or receiving such a 'transmission", electrons (or some other charged object) are, at least in a probabilistic sense, moving back and forth. even at trillions of Hz. eventually frequencies get so high that matter doesn't have much ability to deal with it. i think your DNA would get messed up if you were exposed to enough gamma or cosmic radiation.

    but 91, you just need to accept that visible light is just another set of frequencies in the broad EM spectrum. that's what several other people are trying to confirm to you.
     
  26. May 21, 2007 #25
    Can understand what actually happens with the electrons. They must move when there is presence of magnetic field, so when you move the magnet very frequently you get current, still I can't understand, what actually happens when there is presence of light with high frequency.
     
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