Physics Chapter:
1. Sound is a wave motion, produced by a vibrating source.
2. A medium is necessary for the propagation of sound waves.
3. Sound is a longitudinal wave in which the particles of medium move along the direction
of motion of wave.
4. The part or region of a longitudinal wave in which the density of the particles of the
medium is higher than the normal density is known as compression.
5. The part or region of a longitudinal wave in which the density of the particles of the
medium is lesser than the normal density is called a rarefaction.
6. The point of maximum positive displacement on a transverse wave is known as crest.
7. The point of maximum negative displacement on a transverse wave is known as through.
8. A wave or short duration which is confined to a small portion of a medium at any given
time is known as a pulse.
9. The maximum displacement of particles of the medium from their mean positions
during the propagation of a wave is known as amplitude of the wave.
10. The distance traveled by a wave in one second is called wave velocity. It depends upon
the nature of the medium through which it passes.
11. The speed of sound depends primarily on the nature and the temperature of the
transmitting medium.
12. Sound travels faster in solids than in air. The speed of sound in solids is much more than
the speed of sound in liquids or gases.
13. The distance between two consecutive compressions or two consecutive rarefactions is
called the wavelength.
14. Frequency is defined as the number of oscillations per second.
15. The time taken by the wave for one complete oscillation of the density or pressure of
the medium is called the time period, T.
16. How the brain interprets the frequency of an emitted sound is called the pitch of sound.
17. Loudness is the degree of sensation of sound produced.
18. Sound properties such as pitch, loudness and quality are determined by the
corresponding wave properties.
19. Sound gets reflected and follows the same law as the reflection of light.
20. The persistence of sound due to repeated reflection and its gradual fading away is called
reverberation of sound.
21. Echo is a repetition of sound due to the reflection of original sound by a large and hard
obstacle.
22. The audible range of hearing for average human beings is in the frequency range of 20
Hz – 20 kHz.
23. The amount of sound energy passing each second through unit area is called the
intensity of sound.
24. Sound of frequency less than 20 Hz is known as infrasound and greater than 20 kHz is
known as ultrasound.
25. Ultrasound has many medical and industrial applications.
26. SONAR stands for Sound Navigation and Ranging and it works on the principle of
reflection of sound waves.
27. The SONAR technique is used to determine the depth of the sea and to locate under
water hills, valleys, submarines, icebergs sunken ships etc.
Note Blast 