📝Refraction of Light
Refraction of Light.
When a ray of light, propagating (in a straight line) in one transparent medium, enters another transparent medium, it is observed to (usually) change its direction of propagation or bend its path. We call this phenomenon as refraction of light.
Cause of Refraction of Light.
The speed of light is different in different media. In a vacuum, light propagates at a speed of `3 × 10^8 ms^{-1}`, but when it enters any other transparent medium, its speed decreases. It is this change in speed of light, that causes a light ray to bend when it goes from one medium to another. Thus, refraction is basically due to a change in the speed of light when it goes from one medium to another.
Optical Density
The speed of light, in a given medium, is taken as an indicator of its optical density. We can say that the more is the speed of light in a given medium, the less is its optical density and vice-versa.
Optically denser medium ➨ Lower speed of light.
Optically rarer medium ➨ Higher speed of light.
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