Sound Wave

Sound Waves
Sound waves of all the mechanical waves that occur in nature, the most
important in our everyday lives are longitudinal waves in a medium, usually
air, called sound waves.
Sound waves are of three types
(i) Infrasonic Waves The sound waves of frequency lies between 0 to 20 Hz
are called infrasonic waves.
(ii) Audiable Waves The sound waves of frequency lies between 20 Hz to
20000 Hz are called audiable waves.
(iii) Ultrasonic Waves The sound waves of frequency greater than 20000 Hz
are called ultrasonic waves.
Sound waves are mechanical longitudinal waves and require medium for
their propagation. Sound waves can travel through
[sound waves cannot propagate through vacuum.
If V , V and V are speed of sound waves in solid, liquid and gases, then
V > V > V
Sound waves (longitudinal waves) can reflect, refract, interfere and diffract
but cannot be polarised as only transverse waves can polarised.]
Velocity of Longitudinal (Sound) Waves
Velocity of longitudinal (sound) wave in any medium is given by
CBSE Class 11 Physics Notes Waves and Sound
where, E is coefficient of elasticity of the medium and ρ is density of the
medium.
Newton’s Formula
According to Newton, the propagation of longitudinal waves in a gas is an
isoth. ermal process. Therefore, velocity of longitudinal (sound) waves in
gas should be.