| English | Reflection of waves |
|---|---|
| Bahasa Melayu | Pantulan gelombang |
| 中文 | 波的反射 |
Definition
The bouncing back of a wave when it hits a barrier, with the angle of reflection equal to the angle of incidence.
In exam terms
Reflection of waves is the bouncing back of a wave when it hits a barrier or boundary, staying in the same medium. The angle of reflection equals the angle of incidence, with both angles measured from the normal (the line perpendicular to the barrier).
During reflection the frequency, wavelength and speed of the wave all stay unchanged; only the direction of travel changes. In a ripple tank a straight plane wave reflected off a straight barrier stays a straight plane wave.
An everyday example is an echo, which is sound reflected from a wall back to the listener.
Do not confuse it with refraction
In reflection the wave stays in the same medium and bounces back with unchanged speed and wavelength. In refraction the wave crosses into a new medium, so its speed and wavelength change and it bends.
Watch which is asked: reflection keeps the wave on the same side of the boundary.
In Paper 2 you may be asked to state the law of reflection, or to draw the reflected wavefront or ray in a ripple tank. Always show the normal, mark the equal angles, and keep the wavelength the same before and after.
Source: DSKP KSSM Physics Form 4 and 5 (Versi English) (Bahagian Pembangunan Kurikulum (BPK), KPM)