| English | Refraction of light |
|---|---|
| Bahasa Melayu | Pembiasan cahaya |
| 中文 | 光的折射 |
Definition
The bending of light as it passes from one transparent medium to another because of a change in its speed.
In exam terms
Refraction of light is the bending of a light ray as it passes from one transparent medium into another because its speed changes. When light enters a denser medium (air to glass) it slows down and bends towards the normal; entering a less dense medium it speeds up and bends away from the normal.
The frequency stays the same; the speed and wavelength change. A correct sentence: a ray entering water bends towards the normal because light travels more slowly in water. Refraction is governed by Snell's law, n₁ sin θ₁ = n₂ sin θ₂.
Do not confuse it with reflection
Do not confuse refraction with reflection. In reflection the ray bounces back off a surface and stays in the same medium; in refraction the ray passes into a new medium and changes direction because of a speed change.
A ray hitting glass can do both at once.
In Paper 2, define refraction as the change in direction of light when it passes between media of different optical densities, and explain why a straw looks bent by saying light from the straw refracts as it leaves the water into the air.
Source: DSKP KSSM Physics Form 4 and 5 (Versi English) (Bahagian Pembangunan Kurikulum (BPK), KPM)