Huygens principle - Reflection & refraction of light | Floatheadphysix

We are going to use the wave theory and the Huygens principle to derive the rules of reflection and refraction.

According to Huygens, light is a wave. So Huygens thinks of light as ripples on the surface of a pond. But you have already seen some geometrical properties of light, namely refraction and reflection. So here are some questions

In refraction of light, why does it obey Snell's law? Where does refractive index really come from? Why are the rules of reflection of light true?
In a previous video, we saw how these rules can be derived using the corpuscular theory of light invented by Sir Issac Newton
(if you haven't watched that already, here is the link to it

When we use the wave theory of light, we are going to use the concept of wavefronts to derive these rules. If you are not familiar with wavefronts, here is a quick refresher

The result is really going to surprise you. We will see that using the wave theory and Huygens principle of wavefronts, we end up with some contradicting results.

From an academic point of view, this derivation using Huygens principle is super important in the CBSE class 12 physics syllabus. It's also one of the most confused ones. Hopefully, here you get an intuitive approach to it.

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