Sound is a form of energy that enables the sensation of hearing. It is produced by vibration and travels in the form of longitudinal waves, requiring a medium for propagation. Sound waves can be reflected, refracted, and their speed depends on the properties of the medium. Sound is classified into infrasonic, audible and ultrasonic ranges. Ultrasound has many medical and industrial applications such as sonar, ultrasound scanning, and Doppler effect. Doppler effect is an apparent change in frequency due to relative motion of source and observer. It is used in traffic control, satellite tracking and astrophysics.
2. “SOUND’ is a form of energy, which enables us the
sensation of hearing.
Study of sound helps us,
To know the mechanism of hearing.
To develop techniques to correct speech and hearing
impairments.
To diagnose many medical problems and check the
health states.
To improvements in the acoustics in theaters, concert
halls and cinema halls.
3. The properties of sound
•It is a form of energy.
• Sound is produced by the vibration of the bodies.
• Sound travels in the form of waves
• It propagates as longitudinal waves.
• It requires material medium for its propagation.
• It undergoes reflection and refraction just like light.
• They transfer energy from one region to another.
• Sound can effect the matter
4. •The sound waves travels through solids, liquids, and
gases (In air 331m/s, In water 1440 m/s)
• The speed of the sound waves depends on the
properties of the medium, such as temperature,
pressure, density etc. Ex: In air 331 m/s at 00c, 342
km/s at 180c.
• They travel in a homogeneous medium with constant
speed, provided the temporary is constant.
•When they incident on a surface, the surface set into
vibrations.
• Illustrations two show that sound is produced by the
vibration of the body.
5. Wave length: (λ):-
The distance between the centre's of two consecutive
compressions or rare fractions is called the wave length of
the wave and is denoted by λ.
Frequency(f):
The number of vibrations made by the source in one second
is called frequency of that wave is denoted by ‘f’
Velocity(v):
The distance traveled by wave in one second is called
velocity and is given by V = f λ
6. Reflection of sound waves:
The phenomenon of bouncing back of sound from surfaces
is called reflection of sound.
Echo of sound
A sound caused by the reflection of sound waves from a
surface back to the listener is called Echo
The minimum distance between the listener and the
reflecting surface to hear the Echo is 17 m
Always the Echo is weaker than original sound because a
part of the energy is absorbed by the reflecting surface
Multiple echo’s are due to multiple reflection of sound.
Example whispering gallery of Golgumbuz.
7. Calculations of the minimum distance listener and
reflecting surface to hear Echo.
8. Sound Waves are classified into three types namely,
Infrasonic sounds (frequency less than 20Hz),
Audible sound (frequency › 20Hz and <20000 Hz),
Ultrasonic sound (above 20000 Hz)
Sounds of frequency lesser than 20Hz are called
infrasonic ( subsonic) sounds.
Sounds of frequency range 20Hz to 20000 Hz are called
audible sounds or sound which is heard by human ears is
called audible sound.
9. Ultrasounds:
Sounds of frequencies beyond, 20 KHz are called
Ultrasounds.
Dogs, Cats, Bats, etc can hear ultrasonic sounds.
Frequency range is from 20 KHz to 5 X 105 KHz
Range of wave length from 1.65 cm to 6x10-5 cm
Activity to produce ultrasonic sounds
ULTRASONICS:
“ The branch of science that deals with the study
of ultrasonic sound is called ultrasonic's ”
10. Properties of Ultrasounds :
They are Longitudinal waves,
Travel with velocity of sound,
They undergo reflection and refraction,
They produce heating effect,
Act as catalyst in chemical reactions.
They cause biological effect.
They are highly energetic because of its high frequency.
11. USES:
The study of US waves in a medium gives information
about physical properties like elasticity, Electronic
configuration of atoms, etc.,
They are used in dry cleaning to remove grease and dirt.
U.S is used to manufacture alloys, for mixing of
immiscible liquid to manufacture emulsion for
photographic films.
The can be used to detect crack and flows in metal
moldings.
12. They are used in welding, local heating and drilling small
holes in hard materials.
They used for sterilizing purposes, they serve as insect
repellents, a strong beam of U.S. waves kills bacteria.
They are used to cure neuralgic ( nerve pains) and
rheumatic ( disorders of muscles) pains.
Used in blood less surgery.
Used in breaking of gall stones and stones in kidneys.
The U.S. is most efficiently used in the instruments like
sonar & U.S. Scanner.
13. SONAR
The Acronym (Short form) of
“Sound navigation and Ranging” → Sonar
A device that uses U.S. Waves to measure the distance,
direction, and speed of underwater objects.” is called
SONAR.
• Invented by Paul Langevin, a French Physicist The
invention was inspired by Titanic disaster.
• The parts of sonar are 1) Transmitter and 2) Detector
14. Transmitter:
Produces and Transmitter the U.S. Waves.
Detector:
Detects the reflected U.S. Waves and converts U.S.
Waves into electrical signals.
Working of SONAR:
Transmitter produces U.S. Waves and transmits the
U.S. Waves and these will travel until they strike to an
underwater object and reflected back.
Reflected U.S. Waves return to sonar. Detector
receives the Reflected U.S. Waves and converts it in
electrical signals these signals are interpreted.
15. To calculate the distance of the object:
The time interval between transmission and reception is
recorded and the distance of the object is calculated by
the formula
Where V = velocity if sound wave through water and
t = time taken to transmission & reception
d = distance of the object
16. Ex: U.S. Signals sent by sonar takes 3 sec to return, find
the distance of the object.
V= 1.5 Km/sec t = 3S, d = ?
USES: 1) Used to locate submarines & icebergs
2) Used to determine depth of ocean.
17. ULTRA SOUND SCANNERS:
The instrument which uses U.S. Waves for getting images
of internal organs of human body is called ultra sound
scanner
Note:
The U.S. Waves are used widely in Medical field
because they are less harmful than x-rays.
18. Working of U.S. Scanners:
U.S. waves can be directed at a specific area of the
body.
As the waves pass through the tissues of the body, the
waves get reflected from a region where there is a
change of tissue density.
The scanner displays the images in a static or moving
picture of the inside of the body on the monitor.
19. USES OF U.S. Scanners:
The images produced by U.S. Scanner are analyzed to
obtain information regarding the internal organs. This
technique is used in the following manner.
• Used as diagnostic tool for examining the fluid filled
organs like bladders, kidneys, ovaries etc., tumors,
ailments & abnormalities in organs.
• Used to examine the arterial system the heart, the
pancreas, the urinary tract, the brain, special chord.
20. • U.S. images are used to examine the foetus during
pregnancy to detect congenital and growth abnormalities.
• US scanners are also used to guide surgical procedures.
ECHO CARDIO GRAPHY
The Technique of using U.S. Waves to examine the heart
is called Echocardiography (ECG)
RADAR and its working
21. DOPPLER EFFECT: (In sound & light)
The pitch (frequency) of the whistle of an approaching
train increases for an observer standing on a platform.
Similarly the pitch (frequency) of the whistle
decreases if the train is moving away from the
observer.
Similarly effect is observed when the observer himself
is moving with respect to the sound producing source.
Such type of effect is observed in all types of waves.
From this we can conclude that there is an apparent
change in the frequency of the wave due to the
relative motion between the source and the observer.
This phenomenon is called Doppler Effect.
22. “ The apparent change in the frequency of a wave due
to relative motion between the source of wave and the
observer is called Doppler Effect”
Note: If there is no relative motion between the observer
and the source, the frequency of the wave neither
increases nor decreases. Therefore there will be no
Doppler Effect.
Doppler Effect holds good for all kinds of
Electromagnetic waves.
Doppler Effect in light:
Doppler Effect of light consists of a shift in the wave
length of light emitted by a moving celestial body.
23. According to Doppler Effect there is an apparent
change in the frequency of the waves whenever there is
a relative motion between the source of the wave and
the observer. This is true for all kinds of waves
including light.
Most of the galaxies are source of light and therefore
we can obtain their spectrum.
The spectral lines of most of the galaxies show a shift
towards the red end of the spectrum and amount of
shift depends on the speed of the galaxy. This helps us
to determine the speed of galaxies.
24. Red shift:
The displacement of spectral lines of light received from
a distant galaxy towards longer wavelengths (the red end
of the spectrum) is called red shift.
Note:
when the galaxy is approaching us, the distance between
the source and observer decreases. As a result there is
apparent increase in the frequency of light. Hence red
shift happens.
25. Blue shift:
The displacement of spectral lines of light received from
a distant galaxy towards shorter wavelengths (the blue
end of the spectrum) is called blue shift.
Note:
when the galaxy or star are moving away from us, the
distance between the source and observer increases. As
a result there is apparent decrease in the frequency of
light. Hence blue shift happens.
26. Applications of Doppler Effects:
• Doppler Effect of sound is used to determine the
velocity of submarines.
• Traffic control Authorities use Doppler Effect to detect
velocity of vehicles crossing the speed limit.
The device used to detect the velocity of vehicles
crossing speed limits is called “RADAR GUN”.
• Doppler Effect is used in tracking of artificial satellites.
• Doppler Effect is used in Astrophysics.
• Study binary stars, Saturn rings, galaxy, to estimate the
speed of stars and galaxies.
41. Illustration : 1
Keep a plate on a vessel. Spread a thin layer of saw dust
on the plate. Hit a tuning fork on a rubber pad . The
tuning fork begins to produce sound. Place the stem of
the vibrating tuning fork on the plate. The saw dust
begins to dance. This shows that the tuning fork
produces sound when it is vibrating.
42. Illustration : 2
Place a paper rider on a string of the veena. Pluck the
string. Now the instrument produces sound and at the
same time the paper rider flies off from the string. This
shows that sound is produced by the vibrating bodies.
43. Take big syringe and fit a tiny buzzer
inside it. Connect the buzzer to the
terminal of the battery. Make the
syringe airtight. Pass current to make
the buzzer work. Now we can hear the
sound of the buzzer. Now work the
piston outward and lower the pressure
inside the syringe. The sound becomes
fainter and fainter. This shows that
sound requires material medium for its
propagation.
lustration to show that sound requires material
medium for its propagation
58. Note:
Analysis of spectral lines of stars and galaxies show a
red shift. This indicates that the stars and galaxies are
moving away from us with a greater speeds.
This also indicates that the universe is expanding.
59.
60.
61. RADAR
The Acronym (Short form) of
“Radio Detection And Ranging” → RADAR
A device which uses radio waves to determine the range,
altitude, direction and speed of both moving and fixed
objects is called RADAR.
It also uses microwaves.
Working of radar video
