7. Class IX- Sound
Wavelength
The distance between two consecutive compressions (C) or
two consecutive rarefactions (R) is called the wavelength.
λ
SI unit
Oscillation
Movement back and forth in a regular rhythm.
9. Class IX- Sound
Frequency
The number of such oscillations per unit time
ν
SI unit
ν = 1/T
Pitch
The sensation of a frequency is commonly referred to as
the pitch of a sound.
13. Class IX- Sound
Amplitude
The maximum displacement or distance moved by a point on a vibrating body
or wave measured from its equilibrium position
14. Class IX- Sound
Speed Of Sound
speed, v = distance / time
λ
v = / T
λ
v = ν
speed = wavelength × frequency.
15. Questions and Answers (NCERT)
→Which wave property determines (a) loudness, (b) pitch?
→Guess which sound has a higher pitch: guitar or car horn?
16. Questions and Answers (NCERT)
→Calculate the wavelength of a sound wave whose frequency is 220 Hz
and speed is 440 m/s in a given medium.
→A person is listening to a tone of 500 Hz sitting at a distance of 450 m
from the source of the sound. What is the time interval between
successive compressions from the source?
