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Question
Derive Snell’s law of refraction using Huygens’s wave theory.
Solution
AB - Incident wavefront
A'B' - Refracted wavefront
i = ∠CAN = ∠BAA'
r = ∠NA'a' = ∠AA'B'
`therefore "sin i"/"sin r" = "BA′"/"AB′"`
BA' = V1 t ; AB = V2t
`therefore "sin i"/"sin r" = ("V"_1)/("V"_2)`
`("V"_1)/("V"_2)` is called refractive index, it's constant for two particular optical medium.
∴ `"sin i"/"sin r" = "constant"`
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