Question

In: Physics

Some people are surprised by the statement that “light does not always travel at the speed...

Some people are surprised by the statement that “light does not always travel at the speed of light.” What does that mean? What are the implications of “slow light”? What are the phenomena that result, and practical applications come from the fact that light sometimes travel slower than the value ? = ? × ????/?.

Solutions

Expert Solution

According to Einstein's 'Theory of Relativity' nothing is faster than the speed of light (Electromagnetic waves) in vacuum,and it's value is given as 3 x 108 m/s .

But when light travels through different mediums, it interacts with the particles (molecules,atoms,ions)  within it ,through denser media because more particles get in its way, each time the light bumps into a particle of the medium, the light gets absorbed which causes the particle to vibrate a little and then the light gets re-emitted. Thus as we know the velocity of the light

V = Frequency X Wavelength

the frequency of the light wave remains unchanged in this process ,but as the velocity changes then according to the relation wavelength of the light changes.

If we know the refractive index of the medium then

Refractive Index of the medium (mu) = The ratio of the velocity of light in a vacuum to its velocity in that medium.

= C / V


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