We know that E x B gives the direction of propagation of an em wave.=> if the direction of propagation is along +z and E, along +x then B is also along +y, and if E is along -x, then B is also along -y ( fig. attached). Now my question is if we are able to see the very first waveform of an em wave ( for instance using a light bulb) then, considering +z as its direction of propagation, will the E be along +x or -x /will B be along +y or -y for the very first waveform?
The directions of the fields in the very first wave is opposite to those in the wave number zero, which in turn is opposite to that in the "very minus first" wave (wave here is half a period).
Look, you are talking about function sin(x) now!
If you try to amend your example, you probably will come to Bose-Einstein condensates, and perhaps to influence of a measurement on a quantum system... I mean, these are things to read about, if you are interested to learn something around your question.
thanks Vladimir, and it seems i got a little homework..If you please explain the first sentence a little more, i will be happy.
T.Y.@ -- Well, your question is formulated in a bit confusing way, but if I understand it correctly (i. e. "will E & B in the very first arrival of the wave polarized in the same planes as for "developed" field?"), the answer is YES. The subject of the "precursor" of EM-field is a very old one (I believe you can find its discussion in Stratton book), and polarization is not the most interesting thing about it. But as far as your question, you may think of the precursor as a combination of infinite number of spectral components (Fourier decomposition), each one being a plane wave, for each one of them a regular fields arrangement should apply. But there are many other, really exciting things. For example, if your wave propagates in a material with certain refractive index, n>1 (so the speed of light is less than "c"), the very tip of the precursor will still move with the speed EXACTLY the same as the speed of light in VACUUM. But this is already wandering away from your subject.
Cheers
@Tarunkishwor -- in you question you used a Fig. where E is shown in the plane XOZ as a function looking like x=sin(z). This function is not confined in the limits of 0
- Badges
- Science topic
- Similar topics
- Physical Sciences
- Optics