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JEE • Physics

Sound Waves

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formula

Displacement and Pressure Excess

The source writes longitudinal displacement and pressure excess for a travelling sound wave.

ξ=Asin⁡(ωt−kx)\xi=A\sin(\omega t-kx)
Pex=−B∂ξ∂x=BAkcos⁡(ωt−kx)P_{ex}=-B\frac{\partial\xi}{\partial x}=BAk\cos(\omega t-kx)
Pm=BAkP_{m}=BAk

Variables & Notation

PP

pressure, power, or source power depending on context

Notes

  • The pressure-excess relation is marked true for travelling and standing waves.