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Reflection of waves
Beginner
Waves bounce at boundaries.
When a wave hits a boundary it bounces back, with the angle of incidence equal to the angle of reflection. Echoes are reflections of sound.
A canyon echo returns after 2d/v.
Frequency doesn't change on reflection.
In more detail
When a wave meets a boundary, part of it reflects back into the original medium. The angle of incidence equals the angle of reflection.
Real-world uses
- Mirrors reflect light, and echoes reflect sound.
- Radar uses reflected radio waves to detect aircraft.
- An echo in a canyon or the mirror-like surface of a calm lake shows waves bouncing back from a boundary.
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Frequently asked questions
Do all waves reflect?
Most waves reflect at boundaries, and the amount depends on the impedance mismatch.
Why do echoes sometimes not return?
If the surface absorbs sound, the reflection is weak.
Does reflection change the wave speed?
No. Reflection sends the wave back into the same medium, so the speed stays the same.
Related topics in Waves & Sound
Wave speed in a medium · Speed of sound · Speed of sound in gases · Phase change on reflection · Refraction of waves · Diffraction