2. Superposition Two particles cannot occupy the same space at the same time, two waves can When two waves interact, one is super imposed on the other The resultant wave is a combination of both waves

3. Constructive Interference Constructive interference occurs when similar parts of both waves occupy the same point in space Transverse Waves Crest meets crest Trough meets trough Longitudinal Waves Compression meets compression Expansion meets expansion Resultant wave with greater amplitude

4. Destructive Interference Destructive interference occurs when different parts of both waves occupy the same point in space Transverse Waves Crest meets trough Longitudinal Waves Compression meets expansion Resultant wave with much smaller (or zero) amplitude

6. Phase Difference Phase difference refers to the alignment of two waves A phase difference of 0° or 360° (0, 2π) means the waves are in-phase Constructive interference A phase difference of 180° (π) means the waves are out of phase Destructive interference

7. Noise Cancelling Headphones Uses destructive interference to eliminate background noise A microphone detects incoming sounds Speaker produces opposite signal, destructively interferes with ambient noise

8. Multi-point interference Waves created by two or more different sources interfere with each other

9. Reflectance When 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

10. Auditoriums vs. Gymnasium