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Author Topic: wave nature and particle nature of light  (Read 2453 times)

Offline tamo kangujam

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wave nature and particle nature of light
« on: 18/02/2014 06:05:28 »
Why does light posses both particle and wave nature? How will the particles of the light focusing on a transparent glass pass through the glass?


 

Offline evan_au

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Re: wave nature and particle nature of light
« Reply #1 on: 18/02/2014 20:22:58 »
One very simplified way of thinking about it is "Light travels like a wave, and strikes like a particle"...
  • In traveling through transparent glass, light acts more like a wave, and is diffracted.
  • In striking the detector in a camera, light acts more like a particle and activates a pixel.

On a human scale, we see long radio waves as more wave-like (partly because the individual photons have undetectably low energy), while high energy gamma rays we view more like particles (partly because the wavelength is invisibly small, plus we currently have no means of producing a coherent beam of gamma rays on which to experiment).

In reality, this is all part of an integrated behavior of light, as described by quantum theory, not two separate natures.
« Last Edit: 18/02/2014 20:32:04 by evan_au »
 

Offline JP

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Re: wave nature and particle nature of light
« Reply #2 on: 18/02/2014 21:22:01 »
One very simplified way of thinking about it is "Light travels like a wave, and strikes like a particle"...
  • In traveling through transparent glass, light acts more like a wave, and is diffracted.

To pick your nits a bit, you can describe light traveling through transparent media (or semitransparent media) using particles.  The wave nature really comes when the light appears to "bend around" corners and obstacles.  If you fired particles at a very narrow slit, you would not expect them to form a wave pattern that appears to spread out in all directions from the slit, but that's just what light does.

Quote
In reality, this is all part of an integrated behavior of light, as described by quantum theory, not two separate natures.
I couldn't agree more.
 

Offline alancalverd

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Re: wave nature and particle nature of light
« Reply #3 on: 20/02/2014 14:25:09 »
There's no "why". Light does what it does, and our mathematical description of its properties takes the form of a macroscopic wave or particle equation depending on the phenomenon we are describing.
 

Offline tamo kangujam

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Re: wave nature and particle nature of light
« Reply #4 on: 21/02/2014 05:13:00 »
Thank you comrades. My another question is what could be that particle made up of? Whether is it particles of the source or something else? Is the fact that light travel in straight line being marred by the fact that light undergoes diffraction? 
 

Offline snowyco

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Re: wave nature and particle nature of light
« Reply #5 on: 21/02/2014 17:49:34 »
Thank you comrades. My another question is what could be that particle made up of? Whether is it particles of the source or something else? Is the fact that light travel in straight line being marred by the fact that light undergoes diffraction?

Your original question contains your answer:  "Why does light posses both particle and wave nature ? "

The point is that light is neither "fish" nor "fowl".   Light simultaneously possesses both   particle   and   wave  natures (properties),   as light is neither wave nor particle.  Huygen's principle of light bending around corners (sharp edges) demonstrates  light's   wave-like  behavior.      Einstein's photo-electric effect demonstrates light's   particle-like  behavior.     

There are no particles in light,  just as waves of light do not need a medium for transmission  (no ether).   Both of these principles are demonstrated by light traveling  just fine in a vacuum.
« Last Edit: 21/02/2014 17:53:03 by snowyco »
 

Offline evan_au

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Re: wave nature and particle nature of light
« Reply #6 on: 21/02/2014 21:07:26 »
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what could [a photon be] made up of? Whether is it particles of the source or something else?
Photons are emitted by electrons and protons changing their orbits (the protons tend to produce gamma rays). The same number of protons and electrons remain in the source material after emitting the photon.

So you would have to say that photons are not particles from the source material, but they do carry away some energy of the source material.
 

Offline snowyco

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Re: wave nature and particle nature of light
« Reply #7 on: 21/02/2014 23:36:45 »
Quote
what could [a photon be] made up of? Whether is it particles of the source or something else?

Photons are emitted by electrons and protons changing their orbits (the protons tend to produce gamma rays). The same number of protons and electrons remain in the source material after emitting the photon.

So you would have to say that photons are not particles from the source material, but they do carry away some energy of the source material.

On an atomic level, protons do not orbit anything. 

Protons do not produce gamma rays.

Nuclear decays (from unstable nucleii rearranging their internal arrangements of neutrons & protons, and emitting alpha or beta particles) and nuclear rearrangements of internal arrangements of neutrons & protons, and nuclear reactions are the primary source of gamma rays.   

Photons can be created by heating matter (see black body radiators - like incandescent light bulbs), where rotating molecules and vibrating molecules emit photons in the Infrared and Microwave ranges, (due to bending, stretching, and compressing chemical bonds), plus producing some (5%) visible light. 

Visible light photons are emitted from electrons moving from higher energy orbital states (NO ORBITS)  down to lower energy states.

X-rays are produced in a variety of ways,  including bremsstrahlung (bending of high energy particle's paths),  and from particle beams or high energy reactions (like in the sun) knocking out inner shell electrons,  and Auger processes.

« Last Edit: 22/02/2014 01:38:05 by snowyco »
 

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Re: wave nature and particle nature of light
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