Talha's Physics Academy
Geometrical Optics - Refraction of Light
Define refraction of light and state laws of refraction.
Refraction of Light
"When a ray of light passes obliquely from one transparent medium into another, its direction of propagation changes at the boundary. This bending of light is called refraction of light."
Two Main Cases in Refraction
- Rarer to Denser Medium: When a ray of light enters from a rarer medium (e.g., air) to a denser medium (e.g., water or glass), it slows down and bends towards the normal.
- Denser to Rarer Medium: When a ray of light enters from a denser medium to a rarer medium, it speeds up and bends away from the normal.
Laws of Refraction
The phenomenon of refraction follows two fundamental laws:
- First Law: The incident ray, the refracted ray, and the normal at the point of incidence all lie in the same plane.
- Second Law (Snell's Law): The ratio of the sine of the angle of incidence ($i$) to the sine of the angle of refraction ($r$) is constant for a given pair of media. This constant is known as the refractive index ($\mu$ or $n$) of the second medium with respect to the first.
Mathematically, Snell's Law is written as:
$\frac{\sin i}{\sin r} = \text{constant} = n$
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