1. Speed of Light:
* Rarer Medium: Light travels faster in a rarer medium (like air).
* Denser Medium: Light travels slower in a denser medium (like water or glass).
2. Wavefronts:
* Light travels in waves. The wavefronts (crests or troughs) are perpendicular to the direction of light propagation.
3. Interaction at the Boundary:
* When light enters a denser medium, the wavefronts encounter a change in speed. The part of the wavefront that enters the denser medium first slows down, while the rest of the wavefront is still traveling at a higher speed in the rarer medium.
4. Bending:
* This difference in speed causes the wavefront to bend, or refract, at the boundary. Since the wavefront slows down in the denser medium, it bends *towards* the normal line.
5. Snell's Law:
This bending is mathematically described by Snell's Law:
* n₁sinθ₁ = n₂sinθ₂
Where:
* n₁ and n₂ are the refractive indices of the two media.
* θ₁ is the angle of incidence (angle between the incident ray and the normal).
* θ₂ is the angle of refraction (angle between the refracted ray and the normal).
Since the refractive index (n) is higher for denser media, the angle of refraction (θ₂) will be smaller than the angle of incidence (θ₁), meaning the refracted ray bends towards the normal.
Analogy:
Imagine a car driving on a smooth road (rarer medium) and then suddenly hitting a patch of mud (denser medium). The wheels on the muddy side will slow down, causing the car to turn slightly towards the direction of the mud. This is similar to how light bends towards the normal when entering a denser medium.
