SuperpositionTwo particles cannot occupy the same space at

the same time, two waves canWhen two waves interact, one is super imposed

on the otherThe resultant wave is a combination of both

waves

Constructive InterferenceConstructive interference occurs when similar

parts of both waves occupy the same point in space

Transverse WavesCrest meets crestTrough meets trough

Longitudinal WavesCompression meets compressionExpansion meets expansion

Resultant wave with greater amplitude

Destructive InterferenceDestructive interference occurs when

different parts of both waves occupy the same point in space

Transverse WavesCrest meets trough

Longitudinal WavesCompression meets expansion

Resultant wave with much smaller (or zero) amplitude

Phase DifferencePhase difference refers to the alignment of

two wavesA phase difference of 0° or 360° (0, 2π)

means the waves are in-phaseConstructive interference

A phase difference of 180° (π) means the waves are out of phaseDestructive interference

Noise Cancelling HeadphonesUses destructive interference to eliminate

background noiseA microphone detects incoming soundsSpeaker produces opposite signal,

destructively interferes with ambient noise

Multi-point interferenceWaves created by two or more different

sources interfere with each other

ReflectanceWhen a wave

encounter a boundary some of the wave is reflected back

The reflectance depends on the material of the boundary

The reflected waves interfere with the incoming waves

Auditoriums vs. Gymnasium