Wave Interactions

Two objects cannot occupy the same space at the same time. However, mechanical waves are not matter, but rather the displacement of matter. This means two waves can occupy the same space at the same time.

There are 4 types of wave interactions: Reflection Refraction Diffraction Interference

Reflection Reflection: the bouncing back of a wave when it hits a surface. * Note: when waves hits a substance some of it is transmitted and some of it is reflected. Transmitted means to pass through This is why we can see objects and hear echoes.

Reflection At a free boundary, waves are reflected but not inverted. At a fixed boundary, waves are reflected and inverted. Wave reflects off Wave reflects off a free boundary a fixed boundary

Refraction Refraction: the bending of waves as they pass through different mediums that cause the speed of the wave to change.

Diffraction Diffraction: change of direction of a wave when it hits an obstacle or edge. Sound diffracts well around corners Light does not diffract as much because the wavelengths are shorter

Interference Interference: when 2 or more waves combine There are 4 types of interference: Constructive interference Destructive interference Standing waves Resonance

Constructive Superposition: the combination of two overlapping waves. When the crests and troughs of different waves match there is constructive interference. They combine to make a wave with larger amplitude

Destructive Destructive interference: when the crest of one wave meets the trough of another The results are a smaller amplitude or no amplitude

Standing Waves Standing Wave: the result of a combination of constructive and destructive interference

Standing waves look like they are standing still, but are not. Standing waves have nodes and antinodes.

The points at which the two waves cancel each other are called nodes. Where the string vibrates with the largest amplitude it is called antinode.

Resonance Resonance : when 2 objects naturally vibrate at the same frequency. The sound produced by one object causes the other to vibrate. Body of a guitar resonates when the strings are strummed