Change in speed and wavelength of light while travelling from one med

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SUMMARY

The discussion focuses on the mechanism by which light changes its speed and wavelength when transitioning between different media, specifically addressing the relationship defined by the equation c/n or λ/n. It is established that while light travels at speed 'c' in a vacuum, its effective speed decreases in optical media due to interactions with atoms, which involve absorption and re-emission processes. The delay caused by these interactions accounts for the observed change in velocity, while the intensity of light remains appreciable in the direction of propagation despite absorption phenomena.

PREREQUISITES
  • Understanding of Maxwell's equations
  • Familiarity with the concepts of speed of light and refractive index
  • Knowledge of photon absorption and emission processes
  • Basic principles of wave-particle duality in light
NEXT STEPS
  • Research the implications of refractive index on light propagation in different materials
  • Study the quantum mechanics of photon absorption and emission
  • Explore the relationship between light speed and wavelength in various media
  • Investigate advanced topics in optics, such as dispersion and interference
USEFUL FOR

Physicists, optical engineers, and students studying wave optics or photonics who seek to deepen their understanding of light behavior in different media.

shantanuphadke
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what is the mechanism by which light changes its speed and wavelength while traveling from one medium to other. I know it is c/n or lamda/n and know it comes from maxwells equations, but what is the physical reason behind this?
 
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Well, if you take one of the two : velocity or wavelength to be changing, change in the other will follow.
For the physical reason behind it, if I'm not wrong, I believe it is the average or effective speed of light that changes in a different optical medium; and between atoms, light still travels at 'c'. If you buy this argument, then to explain the change in velocity of light isn't so hard. The extra time light takes to cover the same distance in say, glass as in vacuum can be attributed to the time lag between the absorption and release of the photon of light by the medium's atoms. And there may be still a lot more going on inside than this.
 
but when particle absorbs light, it gets excited and in the process of de-excitation it emmits light.But that emmited light can follow any direction except the direction in which photon got excited.so we could expect intensity to decrease a lot but it is not observed ( appreciable intesity observed in the direction of propagation).Then how could absorption take place?
 

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