PhysicsChapter 4: Diffraction and Interference
Interference of Sound Waves
Interference of sound
Definition
Interference of sound occurs when sound waves overlap and produce regions of increased or decreased sound intensity.
Constructive Sound Interference
Sound is a longitudinal mechanical wave. Two coherent sound waves can overlap. Compression meets compression and rarefaction meets rarefaction. Result: greater pressure variation and greater sound intensity.
Destructive Sound Interference
Compression tends to overlap rarefaction. Result: reduced pressure variation. For two coherent sources: constructive: **Δr=nλ destructive: Δr=(n+½)λ**
Audible Effect
Moving around two coherent sound sources can produce alternating locations of louder and quieter sound.
Formula / Key Relation
**Δr=nλ → maximum Δr=(n+½)λ** → minimum
Exam preparation
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Review the key facts, formulas and checks before you move on.Interference of Sound Waves
Sticky Notes · Quick Revision
Sound:
- compression + compression → loud
- compression + rarefaction → quiet
60-second revision
- Sound intensity varies spatially because of interference.
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