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I know it happens due to "refraction" but it's a observation. Why doesn't light just travel from one medium to another just straight with a change in velocity?

user8349012
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1 Answers1

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Here's a decent analogy...

Imagine a straight line chain of people holding hands such that each person is holding the hand of two other people. Now imagine they are all walking forward down a road which has tall grass on either side of it.

Now imagine the chain of people is not perpendicular to the side of the road, but tilted in a way that if they all keep walking forward, one end of the chain is going to start walking into the tall grass, which is going to slow them down compared to the other people in the chain. As everyone keeps walking, more people will end up in the grass since that's what they are heading toward eventually. If you look at the whole chain, the section of the chain of people who have to walk slower through the grass will appear to be "bent" with respect to the people who are still walking on the road. Eventually, when everyone's in the grass, the line of people will be straight again, but moving in a new direction different from the original.

The walking chain of people is like a single wave cycle out of many cycles of a classical light "wave"

Apollonius
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  • The bending appear only if the people on grass turn not if they slow down. I do not see how this is an analogy. – Alchimista Aug 06 '17 at 11:10
  • I agree with alchimista though. There should be better explanation.a more scientific one maybe. – user8349012 Aug 06 '17 at 15:55
  • The people in the chain do not have to turn their individual directions. The chain is a pattern made up of the collective positions of the people. Since some people enter the grass before others, the pattern created by the chain of people alters it's tilt angle, but the directions of the individual people in the chain do not change. The chain appears to be moving in a direction that's different than each person individually. Which means each person's neighbors are either ahead of them or behind them a little. – Apollonius Aug 06 '17 at 21:11