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So my question is light travel as wave, so light energy is basically increasing and decreasing electric and magnetic field? How do I visualize it?

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A very short answer, followed by a suggestion.

I can only tell you how I visualise it in wave terms, which is the standard textbook model, but I don't think there is a better way of describing it.

enter image description here

A static picture of an electromagnetic wave is:

From Wikipedia Electromagnetic Waves

enter image description here

The electromagnetic waves that compose electromagnetic radiation can be imagined as a self-propagating transverse oscillating wave of electric and magnetic fields. This diagram shows a plane linearly polarized EMR wave propagating from left to right. The electric field is in a vertical plane and the magnetic field in a horizontal plane. The electric and magnetic fields in EMR waves are always in phase and at 90 degrees to each other.

My suggestion is that you look at these images, and read the Wikipedia article, then post a more specific question on what aspects of the visualisation you don't follow.

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you visualize it when those fields interact with the photoreceptors in your eye, and starting a clear chain reaction whose ultimate purpose is to alert you of any potential changes in the environment

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    $\begingroup$ I'm not sure if when the OP said "how do I visualize it" they meant "how does my eye detect it". $\endgroup$ – M. Enns Jul 31 '16 at 20:27
  • $\begingroup$ The 0P wants to know what this wave looks like as it travels from point A to B. I think everyone has trouble visualizing a wave. It makes more sense if you picture individual oscillating photons. If a single photon traveled 1,000,000,000 miles as a wave how big was that wave?? And did it travel every direction in the universe? That makes no sense. I would picture a photon oscillating at a certain frequency as it travels along at the speed of light. The more the photons the more intense. $\endgroup$ – Bill Alsept Jul 31 '16 at 21:08
  • $\begingroup$ I think the OP is asking, How do electric and magnetic fields interact to produce electromagnetic waves? $\endgroup$ – sammy gerbil Jul 31 '16 at 23:04
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Imagine throwing a stone in a pond. You'll now see waves moving away from where the stone dropped. A pond is a 2D plane, while EM waves travel in 3D. It would behave much like in the pond, but the waves would move away from the source in a spherical way.

The field is increasing and decreasing so theoretically the beam/field of light should have observable dark and light spots. We cannot see this because the frequency of light is roughly 500 THz.

It would be an interesting experiment to proof that these dark spots exist because if they don't, our theory of light and electromagnetism is wrong.

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  • $\begingroup$ Never heard anout interference and diffraction of light? $\endgroup$ – GiorgioP Jan 24 at 6:34
  • $\begingroup$ Diffraction bends light around a corner and interference shows dark and light spots caused by destructive and constructive interaction of two wave sources. None of these proof that a single wave source has dark spots. $\endgroup$ – progonkpa Jan 24 at 9:05
  • $\begingroup$ How could you have destructive interference if amplitudes wouldn't be positive and negative ? $\endgroup$ – GiorgioP Jan 24 at 11:03
  • $\begingroup$ You make good points. I agree with you. It just bothers me that we can't really look at an EM wave up close and instead have to draw conclusions from the fact that electromagnetism displays wave behaviour. $\endgroup$ – progonkpa Jan 26 at 3:39
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  1. In the above pictures there is drawn only the half of the electric and magnetic field component of light. It would be better to draw the north and the south pole of the magnetic field component as well as the full potential difference between plus and minus of the electric field component.
  2. The amplitude of the electric and the magnetic field component of light was never measured. And the electric field of a charge is defined as infinitely extended. But for the definition of light as a wave the amplitude has to be defined. So the square of amplitude was interpreted as the intensity of the given light. And the infinity was explained by the way, that light is a disturbance of an overall existing EM field.
  3. The phase dependence of the electric and the magnetic field components - their shift or no shift - for a laser beam as well as for single photons (if one think in photons) was never measured. For radio waves, which one make from accelerated electrons and by this made by a huge number of photons, for the reasons of discovered EM induction the electric field of the accelerated electrons in the antenna rod bear a magnetic field and this field bear an electric field and so on.

Following this points a sketch of a radio wave in the near field has the next form:

enter image description here

It is from some interest to show what is the discovery property of spin for an EM wave. It could be seen from the last sketch that there is a asymmetry in the relation between the directions of the electric und the magnetic field component. The blue and red arrows (representing the magnetic B-field and the electric E-field) follow each other anti-clockwise if one have a look in the direction of propagation. There is exactly one other possibility of arrangement of the field components. This shown in the second sketch:

r

For more clearness of what is an EM radiation, a photon and a radio wave see What is the relation between electromagnetic wave and photon?.

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    $\begingroup$ I think the two picture are false, the E and B field should be in phase as in the picture in count_to_10 answer. The "spin" of EM waves comes from the phase between the two normal components of the E field, not between the E and B fields $\endgroup$ – EigenDavid Aug 2 '16 at 10:41
  • $\begingroup$ @David "Following this points a sketch of a radio wave has the next form." How do you think the near field radiation looks like? $\endgroup$ – HolgerFiedler Aug 2 '16 at 12:14
  • $\begingroup$ @David commons.m.wikimedia.org/wiki/… $\endgroup$ – HolgerFiedler Aug 2 '16 at 12:34
  • $\begingroup$ It's not clear in your text that you are talking about the near field (but yes in the nearfield E and B are out of phase). When one talks about radiation, one refer usually to the far field. What you say is not wrong but I think it can really confuse OP. $\endgroup$ – EigenDavid Aug 2 '16 at 12:47
  • $\begingroup$ @David what are the two components of the E field? $\endgroup$ – HolgerFiedler Aug 2 '16 at 13:27

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