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everyone I'm new here, but not so new in physics. 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 ftom the point of an oscillating charge, but there is only electric field shown. e.g.

enter image description here

enter image description here

It tells me that is something like this

enter image description here

and that these circles are magnetic field of moving charge, but they are actually showing crest or trough of an electric field, i.e. electric wave, right?

So another question follows, is electromagnetic wave really how it looks like in many pictures and animations? e.g.

enter image description here

Forgive me for my bad english, it is not my native language and I'm not using it very often.

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  • $\begingroup$ There is an article on wikipedia which shows a picture of electric and magnetic fields of dipole radiation. $\endgroup$
    – Physicist137
    Commented Mar 11, 2015 at 20:07
  • $\begingroup$ thanks, but I hope if you or someone else could post picture for me as a picture above, the second from the top, but with magnetic field lines that creates em wave, or just download that picture, draw magnetic field lines and then post it, I would be very appriciative, and of course I will go through that article you gave me $\endgroup$
    – coon
    Commented Mar 11, 2015 at 20:58

3 Answers 3

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For electrodynamics simulations I have found the following applets particularly useful.

www.falstad.com

Below is a screenshot of the TE electrodynamics simulation showing a still frame of the electromagnetic fields of an oscillating electric dipole. The arrows represent the strength and direction of the electric field. The magnetic field is represented by red and green shading for magnetic field into and out of the screen respectively.

You can control the frequency of the waves and what fields are displayed - enjoy; I have.

Electrodynamics simulation from www.falstad.com

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  • $\begingroup$ thanks man, but I hope if you (or someone else) could post picture for me as the second from the top, but with magnetic field lines, or just download that picture, draw magnetic field lines and then post it, I would be very appriciative, as I am now, thanks again. I just want to confirm what I figured out from your answer. I have worked a little bit with TE electrodynamics simulation and applied knowledge about electromagnetism but I am getting hard to understand it (I am not god at electromagnetism and I am a rookie). $\endgroup$
    – coon
    Commented Mar 12, 2015 at 19:00
  • $\begingroup$ @coon why don't you take a look at the applet, field lines are possible, though look messy in my view. $\endgroup$
    – ProfRob
    Commented Mar 12, 2015 at 19:02
  • $\begingroup$ oh, ok, I get it $\endgroup$
    – coon
    Commented Mar 12, 2015 at 19:58
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It is very easy to get the magnetic field from the electric field: at any point take the cross-product of the direction of propagation with the direction of the electric field, and the result is the direction of the magnetic field! And the magnitude of H is that of E divided by $Z_0$, which is 377 ohms.

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  • $\begingroup$ Isn't that only true for the radiation field? If you had a charge at rest, there is a nonzero electric field, but the $\vec{B}$ field is zero. $\endgroup$
    – Timaeus
    Commented Mar 11, 2015 at 23:39
  • $\begingroup$ Yes, it's for the radiation field, which is what the question seems to be about. $\endgroup$
    – TimeVariant
    Commented Mar 11, 2015 at 23:55
  • $\begingroup$ The question included multiple pictures that had the charge in it, and near the charge you have to compute the actual $\vec{B}$ field, and they wanted actual pictures, so actual pictures should get the $\vec{B}$ field correctly. For instance, those circles in the third picture are not $\vec{B}$ field lines. $\endgroup$
    – Timaeus
    Commented Mar 12, 2015 at 1:10
  • $\begingroup$ 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 picture or animation of an electric and magnetic fields together from the point of an oscillating charge, to make conection. 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, and I didn't know that isn't possible to do something like that $\endgroup$
    – coon
    Commented Mar 13, 2015 at 17:03
  • $\begingroup$ and please do not get me wrong, I'm not being insolent, I do admit that's my bad $\endgroup$
    – coon
    Commented Mar 13, 2015 at 17:14
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Another, much more rudimentary visualisation is available on JavaLab under the Electromagnetic Wave chapter. Sadly, this is only for a constant-frequency oscillation. But you may find it a suitable complement to Falstad.

enter image description here

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