1.3 Introduction
1.3.1 Characteristics of Sound - Pressure Variations
1.3.2 Characteristics of Sound - Speed of Sound
1.3,3 Characteristics of Sound - Pitch Loudness and Timbre
1.3.4 Characteristics of Sound - Intensity
1.3.5 Doppler Effect
Unit 2.1 Multiple Choice Extended Questions - Waves
Unit 2.1 Multiple Choice Extended Answers-Waves
Unit 1.3 Multiple Choice Questions - Sound
Unit 1.3 Multiple Choice Answers - Sound

Unit 1.3 Sound Waves

Characteristics of Sound

1.3.1 Pressure Variations in Sound Waves

pressure wave

Sound waves may be called pressure waves.

It is obviously easier to measure a pressure than the displacement of the molecules.

We can represent the harmonic position as:

s(x,t) = smax cos (kx-ωt)

and the variation in pressure as:

ΔP = ΔPmax sin (kx-ωt)

It is important to note that the displacement wave is one quarter wave (φ = π/2) ahead of the pressure wave.

As the pressure is highest in the equilibrium position and zero where the displacement is maximum (crests and troughs of the displacement wave).



1. The wind is blowing over the top of an open hollow fence post made of pipe tubing to create a continuous pulses which runs down the pipe and is reflected back up the pipe. Describe the pressure and displacement of air particles at the bottom of the pipe.

Answer = .....


Concept by Kishore Lal. Programmed by Kishore Lal... Copyright © 2015 Kishore Lal. All rights reserved.