sound topic fully covered

1. Anusha mishra
SOUND

2. WHAT IS SOUND?
Sound is a form of energy, which
produces a sensation of heating in our
ears. When a body vibrates, sound is
produced. So, each source of sound is a
vibrating body. Sound cannot travel in
vacuum. It needs a material medium for
its propagation. Sound can travel in solids,
in liquids as well as in gases. Its speed is
maximum in solids, less in liquids and

3. MOST COMMON
EXAMPLE
When a tuning fork is struck on hard
rubber, it will move from the mean position
A to the extreme position B towards the right,
then it will again come back to mean position
A, and then to the extreme position C to the
left and finally back to mean position . This to
and fro motion of the fork about its mean
position called one vibration. All vibrating
bodies produces sound

4. AMPLITUDE: THE MAXIMUM DISPLACEMENT
OF A VIBRATING BODY FROM ITS MEAN POSITION IS
CALLED AMPLITUDE.
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5. FREQUENCY: THE NUMBER OF VIBRATIONS
PRODUCED BY A BODY IN A SINGLE SECOND A IS
CALLED FREQUENCY. IT IS DENOTED BY LETTER UNITS
OF FREQUENCY: WHEN A VIBRATING BODY PRODUCES
ONE VIBRATION IN SECOND THEN ITS FREQUENCY IS
SAID TO BE ONE HERTZ .
(I)1 KHZ 1000 HZ
(II) 1 MHZ= 1000,000 HZ.
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6. TIME PERIOD: THE TIME IN WHICH A
VIBRATING BODY COMPLETE ONE VIBRATION IS
CALLED TIME PERIOD. IT IS DENOTED BY LETTER T.
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7. DO ALL VIBRATIONS PRODUCE
SOUND?
It has been proved that human ear is not
sensitive for all frequencies. If the frequency of
the vibrations is less than 20 Hz. Then human
ear cannot perceive them. . If the frequency of
vibrations is between 20 Hz to 20,000 Hz then
they can be perceived by human ear. Such
vibrations are called sonic vibrations or sound
vibrations. It has been further found that the
higher the frequency, the sharper or shriller is
the effect on sound at the ears . However, if the
frequency of vibrations is above 20,000 Hz then
the human ear cannot perceive them. Such
vibrations are called ultrasonic vibrations or
ultrasonics.
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8. ECHOES
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If you stand in front of a high building or a hillock, such that you are at a
distance of more than 20 m and shout loudly, you will notice that you can
hear your own sound. It is because the sound is reflected from the
building. This hearing of reflected sound is called echo.
Why is an echo formed?
Human ear can hear two sounds separately only if they reach the ear
after an interval of 1/10 of a second. This is a natural feature of any
human ear. The average speed of sound is 33 ms.
And echo cannot be also not produced if there are sound absorption
objects in that place
like ; gunny bags ,tables ,etc

9. SONAR
A device fitted in a ship to find the depth
of sea is called sonar. It is based on the
principle of reflection of sound. From the point
A, ultrasonic vibrations are sent. These
vibrations, after striking the sea bed, get
reflected upward and are picked up at point B.
The time in which reflected sound is received is
recorded . Knowing the speed of sound in
water (1500 m/s) and the time taken for the
reflected sound to reach the sonar, the depth
can be calculated as illustrated by the example
given below :

10. MONOTONE
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Monotone: When someone speaks in a monotone, his voice is flat and boring and
everything sounds the same. A continuous especially someone's voice, that does not rise
and fall in pitch, is a monotone.

11. UNIT OF LOUDNESS IN DECIBELS
The loudness of sound is measured in decibels (db).
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12. THANK YOU
Anusha Mishra