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Photons acceleration in refraction

  1. Sep 2, 2015 #1
    In transparent matirials it is known that when light going through it ,photones speed in the matirial would be smaller than in a vaccum.

    When the light refractioning, the photones transfer from one transparent media to another (for example- Vaccum to water).
    The photones during the process changing their diraction manifested by the change between the hit angle and the refraction angle.

    From those data`s:
    Does the photones get accelration because the changing of the amount and direction of the speed during the refraction, does according to the second Newton law there is a force that making photones get accelration while they transfer from one transpernent media to another?
    could it be simillar to the general reatvility that the light getting curved next to stars because the space getting curved due to the gravitation influence from the star?
    Or maybe it could be because of the qualities of the light - zero mass photones, and dual particle-wave behavior?
  2. jcsd
  3. Sep 2, 2015 #2


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    What can you do with Newton's law when m = 0, as it is with photons ? :smile:
  4. Sep 2, 2015 #3
    What is making the light change speed and direction if not force?
    Does it some field source from another place?
    Or it is related with the ingestion of photones by the molequals of the transprant matirial such as H2O- water?
  5. Sep 2, 2015 #4
    E=mc^2 (mass-energy eqution)
    E=hf( photon energy)
    F=ma (newton 2nd law)
    hf=mc^2(equlize vboth of the energy eqution to find mass)
    F=hfa/c^2 (we put the data about the mass in Newton`s law)
    a=dv/dt (the accleration eqution)
    dv=c(vaccum)-v2(water) (we found dv by the substraction speeds of light in vaccum with the speed of light in water)
    dt=???? - what the time is taking the light to transfer from speed in vaccum to the speed in water???
    Last edited: Sep 2, 2015
  6. Sep 2, 2015 #5


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    The change of speed causes the refraction. The speed in different media is lower than the speed in vacuum because within the medium the electromagnetic field (light is an electromagnetic wave) behaves differently (google permittivity and magnetic permeability).

  7. Sep 2, 2015 #6


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    Photos aren't like little tiny objects moving through space. They aren't subject to forces in the way that you're thinking, they don't have a path or a position as you understand those words, and the mental model that you formed when you first heard the word "particle" in this context is misleading you badly. So the first step in understanding refraction is to forget everything you think you know about photons.

    Once you've done that, there are two ways of understanding refraction. (The first is a prerequisite for the second, so you might as well start there).
    1) Use ordinary classical wave optics; treat the light as a classical electromagnetic wave and analyze its behavior as it passes through the boundary between air and water. The concept of photon doesn't even appear. The science here was well understood and widely used long before quantum mechanics was discovered
    2) Use the methods of quantum electrodynamics (QED), where the photon does appear but is treated correctly, as a quantized excitation of the field instead of what you're thinking when you hear the word "particle". The mathematical price of admission here is quite steep - it would be unusual for someone in a undergraduate college program to be ready to study QED - but Richard Feynman has written an excellent and layman friendly book that you might try.
  8. Sep 2, 2015 #7


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    Dani, at what level would you like assistance ?
  9. Sep 2, 2015 #8
    I want to get a profesor diploma and be theoretical physist, I graduated from high school with high grades in physics and mathematics.

    right now I service my last year in army,(in my country you must service at least 3 years) I work in artillary corps as calculator of balistic datas and transfering them to the cannons to make them hit the targets directly and in the right power.

    I often watching lectures in the internet,
    and reading scientific articles, and books from Michio Kaku, Stephan Hoking, Mario Libio...

    I hope after this year i would teach physics in the university, and advance to go forward for research and maybe one day meet the greatest mind scientists in the world and even co-operate with them.

    I know im a dreamer and i have long and hard way before me, I also need to invest and teach from begining all the basic rules.

    I see this forum as a beginning and helping tool for my journy... so i would like to assist more theoretical physics information then matematical for now till I learn this in university...
    I can understand General and special realtivity ,basic mechanics optitcs and elctromagnetism
    and theoreticlly quantum mechanics and the standart module.
    Last edited: Sep 2, 2015
  10. Sep 3, 2015 #9


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    It's that and much more, which you'll come to realize if you stay around as long as I have. Joined: Nov 28, 2003 :approve:
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