How Does Light Slow Down in Different Media?

In summary, at the microscale, the phase speed of an electromagnetic wave is slowed down in a material due to disturbances created by the electric and magnetic fields on the charges of each atom. This results in the charges producing their own electromagnetic wave at the same frequency, but with a phase delay. When these contributions are combined, they create a wave with the same frequency but shorter wavelength, leading to a slower phase speed. This phenomenon is known as refraction and is described by the refractive index. The oscillation radiator cannot radiate waves backward due to the superposition of all the contributions in the material. This concept is not commonly discussed in threads about this topic.
  • #1
einstein1921
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At the microscale, an electromagnetic wave's phase speed is slowed in a material because the electric field creates a disturbance in the charges of each atom (primarily the electrons) proportional to the electric susceptibility of the medium. (Similarly, the magnetic field creates a disturbance proportional to the magnetic susceptibility.) As the electromagnetic fields oscillate in the wave, the charges in the material will be "shaken" back and forth at the same frequency.[13] The charges thus radiate their own electromagnetic wave that is at the same frequency, but usually with a phase delay, as the charges may move out of phase with the force driving them (see sinusoidally driven harmonic oscillator). The light wave traveling in the medium is the macroscopic superposition (sum) of all such contributions in the material: The original wave plus the waves radiated by all the moving charges. This wave is typically a wave with the same frequency but shorter wavelength than the original, leading to a slowing of the wave's phase speed.(Citation http://en.wikipedia.org/wiki/Refractive_index)
1.why wave's phase speed is slowed ? please give more explanation.
2. why the oscillation radiator can't radiate wave backward?
Thank you!
 
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  • #2
I know there are thread talk about this topic, However,none of them discuss the superposition model. anybody can help?
 

1. How does light travel through different mediums?

Light travels through different mediums by interacting with the particles in the medium. When light enters a medium, it can either be absorbed, reflected, or transmitted. The type of interaction depends on the properties of the particles in the medium and the wavelength of the light.

2. Why does light slow down when it passes through a medium?

Light slows down when it passes through a medium because it interacts with the particles in the medium, causing it to be absorbed and re-emitted. This process takes time and results in a decrease in the speed of light in that medium. The more dense the medium, the more interactions occur, and the slower the speed of light.

3. Can light travel through all mediums?

No, light cannot travel through all mediums. It can only travel through transparent mediums that allow light to pass through with minimal absorption or scattering. Opaque mediums do not allow light to pass through at all, and translucent mediums only allow some light to pass through.

4. How does the refractive index of a medium affect the speed of light?

The refractive index of a medium is a measure of how much the speed of light is reduced when it passes through that medium. The higher the refractive index, the slower the speed of light in that medium. This is because a higher refractive index means there are more interactions between the light and the particles in the medium.

5. Does the wavelength of light affect how it travels through a medium?

Yes, the wavelength of light does affect how it travels through a medium. Shorter wavelengths, such as blue or violet light, are more easily absorbed and scattered by particles in the medium compared to longer wavelengths, such as red or orange light. This is why we see different colors when light passes through a prism or when it travels through different mediums.

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