File talk:Light-wave.svg

I know this is a popular representation of the oscillating electric and magnetic fields, but I think it might be wrong. Shouldn't the E field be at a maximum when the B field is at a minimum and vice versa? Not both at a maximum at the same time. —Preceding unsigned comment added by CallipygianSchoolGirl (talk • contribs) 01:26, 14 March 2008 (UTC)


 * E field is at a maximum when the B field is at a minimum only for electromagnetic standing wave and not for traveling electromagnetic wave. This common misconception occurs when one sees from the Maxwell's equations that changing E causes B and changing B causes E, but if one looks closer then one sees that E changing in time causes B changing in space and vice versa.
 * Hope this helps to understand why are em waves the way they are. :) --193.198.16.211 (talk) 10:35, 26 March 2008 (UTC)


 * CallipygianSchoolGirl is right, for EM waves the E and B fields have a 90degrees offset. Doesn't matter if the waves are standing or not. The E field is minimum when the B field is maximum. —Preceding unsigned comment added by Headbomb (talk • contribs) 14:31, 10 April 2008 (UTC)


 * Any other comments? If this image is wrong, and I think it might be, it *NEEDS* to be corrected or deleted. The page on photons used it pretty prominently. CallipygianSchoolGirl (talk) 04:39, 29 May 2008 (UTC)

I take bad what I said back then. There is no 90 degree offset, and I really don't understand how I thought there was an offset. The image is correct. You can check Hecht's Optics, or Goode's Classical Electromagnetism for proofs that the fields are in phase. If you need further proof (or can't access the books and don't want to take what I said at face value), I'll dig it up and give you a direct quote. I've mentioned this elsewhere on wikipedia, but I don't remember where.

Anyway, image is accurate. Headbomb {ταλκ – WP Physics: PotW} 02:21, 24 June 2008 (UTC)


 * Agreed. In Griffiths's E&M textbook (3rd edition, Example 9.2, p379) an electromagnetic wave is drawn exactly as in this picture. The nodes of E and B are at the same points. (That's for a monochromatic plane wave in vacuum.) Then if you look ahead to section 9.4, he writes that E and B have a phase difference only if they're in an absorptive medium (e.g., a conductor). In fact, the tangent of the phase-difference is proportional to the wavelength divided by the absorption length.


 * Anyway, I second that the image is accurate. :-) --Steve (talk) 02:24, 24 June 2008 (UTC)

The image is wrong in that the electric and magnetic field labels should be switched. This image for example is correct: http://en.wikipedia.org/wiki/File:Electromagneticwave3D.gif Htexmexh (talk) 13:40, 14 July 2013 (UTC)

Suggestions

 * M should be changed to B, as this is what is used in any textbook out there.
 * The wave-vector $$\vec{k}$$ should be featured somewhere.
 * Image should be flipped, so the wave propagates from left to right, not from right to left as it currently stands.

Headbomb {ταλκ – WP Physics: PotW} 17:09, 25 June 2008 (UTC)