Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: katieHaylor on 16/07/2017 21:39:53
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Pratheek says:
Why does light bend when it travels between media of different densities?
What do you think?
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The critical factor is not density, but refractive index, which is a measure of the amount that light slows down when it enters the material.
Some examples of refractive Index values (https://en.wikipedia.org/wiki/List_of_refractive_indices) (it varies with color, but typical values):
- Vacuum = 1 (by definition)
- Air = 1.000293
- Water = 1.330
- Glass = 1.5
- You will notice that these are actually increasing in density too - but there are exceptions like diamond which has a refractive index of 2.4, but is made of the relatively light element carbon
If you consider light from a laser to be a linear wavefront striking a material at an angle, where this material has a with a lower speed of light than the source material:
- Part of the wavefront will be in the slower material and travel less distance in a given time
- Part of the wavefront will be in the slower material and travel more distance in the same time
- This bends the path of the light
- A bit like ocean waves reaching the coast; they move slower in shallower water, and so bend inwards towards the coast
See: https://en.wikipedia.org/wiki/Refraction