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1. {SOUND}
MADE BY :
PRATIKSHA YADAV
Class : 9th

2. Contents
•
Introduction
•
propagation of sound
•
wave
•
types of wave
•
characteristics of sound wave
•
frequency
•
amplitude
•
speed
•
Reflection of sound
•
reverberation
•
Range of hearing
•
SONAR
•
Human ear

3. introduction
Sound is a form of energy which produces
a sensation of hearing in our ears.

4. Propagation of sound
 Sound is transmitted by particles (atoms or
molecules) in a solid, liquid or gas colliding
with each other. It is a wave which is created by
vibrating objects and propagated through a
medium (solid, liquid or gas) from one location to
another.

5. Wave
The disturbance created in a
medium ( solid , liquid , gas ) .

6. Types of wave
Longitudinal waves – the wave in which the
particles of medium vibrates to and fro in the
same direction in which wave is moving.
Transverse wave – the wave in which the particles of
medium vibrates up and down to the direction in
which the wave is moving .

7. Frequency
Amplitude
speed

8. Frequency
• The frequency is the number of
wave created
Per second is called frequency .

9. Amplitude
Amplitude is the magnitude of change in the
oscillating variable with each oscillation within
an oscillating system.

10. Speed
The speed of sound depends on the
medium the waves pass through .

11. State
state
solids
liquids
Gases
substance
Iron
steel
Water (sea)
Water
(distilled)
air
oxygen
Speed in m/s
5950
5960
1531
1498
346
316

12. Reflection of sound
• Multiple reflection of sound is the process in
which sound waves bounces off
obstacles and reflects many times before reaching the
destination. this is the
phenomena that occurs in a stethoscope. sound waves
reflect through the
tube many times before reaching the ears of the
doctor. It is very helpful in
detecting problems.

13. Reverberation
• Reverberation is the persistence of sound in a
particular space after
the original sound is removed. A reverberation,
or reverb, is created
when a sound is produced in an enclosed space
causing a large number
of echoes to build up and then slowly decay as the
sound is absorbed by
the walls and air.

14. Range of hearing
• Hearing range usually describes the range of
frequencies that can
be heard by an animal or human, though it can
also refer to the range of levels.
In humans the audible range of frequencies is
usually said to be 20 Hz (cycles per second) to
20 kHz (20,000 Hz) .

15. SONAR
Sonar stands for sound navigation and
ranging .
Sonar is a device that uses ultrasonic waves
to measure the distance , direction and speed
underwater objects .

16. Human ear
The ear is the anatomical organ that
detects sound. It not only acts as a
receiver for sound, but also plays a major role
in the sense of balance and
body position. The ear is part of the auditory
system.

18. [MCQs]

19. A sound wave travels from east to west, in
which direction do the particles of air
move?
(A) East – west
(B) North - south
(C) Up and down
(D) None

20. . In which medium sound travels
faster ?
(A) Solid
(C) Gas
(B) Liquid
(D) None

21. What is the name of short duration
wave?
(A) Pulse
(C) Time period
(B) Frequency
(D) Velocity

22. What is the velocity of sound in
water at room temperature?
(A)1500 m/s
(B) (B) 330 m/s
(C) 1500 km/s
(D) 330 km/s

23. The unit of quantity on which pitch
of the sound depends is :
(A)Hertz
(B) meter
(C) meter/second
(D) second

24. The unit of quantity on which
loudness of found depends is :
(A) meter
(B) Hertz
(C) meter/second
(D) second

25. Nature of sound wave is :
(A) transverse
(B) longitudinal
(C) electromagnetic
(D) seism

26. Pitch of high frequency sound is :
(A) high
(C) zero
(B) low
(D) infinite

27. Voice of a friend is recognized by its :
(A) Pitch
(C) Intensity
(B) quality
(D) velocity

28. Sound waves in air are :
(A)Longitudinal waves
(B) Radio waves
(C) Transverse waves
(D) Electromagnetic waves

29. 1-A
3-A
5-A
7-B
9-B
2-A
4-A
6-A
8-A
10-A