IGCSE Physics\Sound\Important Concepts
IGCSE PHYSICS
SOUND: IMPORTANT CONCEPTS
Sound wave is the form of wave caused by rhythmic vibration of particles in a
medium, causing sound energy to be transmitted from one point to another.
Production and propagation of sound waves:
(a) Sound waves are produced due to vibration of a source, which causes particles
in the medium to vibrate rhythmically.
(b) As the particles in the medium are compressed and rarefied repeatedly, sound
energy is transmitted through the medium.
Example: Production of sound wave by a tuning fork and propagation of sound
wave in air
Important:
Compression of air molecules results in regions of high pressure; rarefaction of
air molecules results in regions of low pressure.
The distance between successive compressions/ rarefactions gives the
wavelength of the sound wave.
Properties of sound waves:
(a) Sound waves are longitudinal waves.
(b) Sound waves require medium for propagation.
(c) Sound waves exhibit waves properties such as reflection and refraction. A
reflected pulse of sound is known as an echo. Production of numerous echoes
by different reflecting surfaces results in reverberation.
(d) A normal human ear is able to detect sound between the frequencies of 20 Hz
and 20 000 Hz. A sound wave below 20 Hz of frequency is known as an
infrasound, while that above 20 000 Hz is known as an ultrasound.
Factors that affect the speed of sound:
(a) Density of medium of propagation: higher density of medium results in higher
speed of sound, i.e. the speed of sound in solids is the highest, followed by
liquids and gases.
(b) Temperature of medium: higher temperature of medium results in higher
speed of sound.
_____________________________________________________________________________
Nakazawa EduServ. Created by Jackson Tik, B.Sc. (NUS). ©All rights reserved.
1
IGCSE PHYSICS
SOUND: IMPORTANT CONCEPTS
Sound wave is the form of wave caused by rhythmic vibration of particles in a
medium, causing sound energy to be transmitted from one point to another.
Production and propagation of sound waves:
(a) Sound waves are produced due to vibration of a source, which causes particles
in the medium to vibrate rhythmically.
(b) As the particles in the medium are compressed and rarefied repeatedly, sound
energy is transmitted through the medium.
Example: Production of sound wave by a tuning fork and propagation of sound
wave in air
Important:
Compression of air molecules results in regions of high pressure; rarefaction of
air molecules results in regions of low pressure.
The distance between successive compressions/ rarefactions gives the
wavelength of the sound wave.
Properties of sound waves:
(a) Sound waves are longitudinal waves.
(b) Sound waves require medium for propagation.
(c) Sound waves exhibit waves properties such as reflection and refraction. A
reflected pulse of sound is known as an echo. Production of numerous echoes
by different reflecting surfaces results in reverberation.
(d) A normal human ear is able to detect sound between the frequencies of 20 Hz
and 20 000 Hz. A sound wave below 20 Hz of frequency is known as an
infrasound, while that above 20 000 Hz is known as an ultrasound.
Factors that affect the speed of sound:
(a) Density of medium of propagation: higher density of medium results in higher
speed of sound, i.e. the speed of sound in solids is the highest, followed by
liquids and gases.
(b) Temperature of medium: higher temperature of medium results in higher
speed of sound.
_____________________________________________________________________________
Nakazawa EduServ. Created by Jackson Tik, B.Sc. (NUS). ©All rights reserved.
1
