In this post, you will find NCERT Science Class 8 Chapter 13 activity 13.11 and after reading this, you can understand the meaning of sound, characteristics of sound, propagation of sound, properties of sound, and types of sound waves. You should also go through activity 13.9 of chapter 13.
Activity
·
Take a metallic tumbler and a tablespoon.
·
Strike the tablespoon gently at the brim of
the tumbler.
·
Hear the sound produced.
·
Now bang the spoon on the tumbler and hear the
sound produced again.
·
Is the sound
louder when the tumbler is struck hard?
·
Now suspend a small thermocol ball touching
the rim of the tumbler.
·
Vibrate the tumbler by striking it.
·
See how
far the ball is displaced.
·
The displacement of the ball is a measure of
the amplitude of the vibration of the tumbler.
·
Now, strike the tumbler gently and then a
little harder.
·
Compare the amplitudes of vibrations of the tumbler
in the two cases.
·
In
which case is the amplitude larger?
Activity 13.11 Class 8 Science Chapter 13 Solution |
Observation and explanation
When we strike the tablespoon
gently at the brim of the tumbler, it produces sound.
Now we bang the spoon on the tumbler,
this time sound produced is louder than the previous action.
So the sound is louder when the tumbler is struck hard.
Now we suspend a thermocol ball touching the brim of the tumbler and hit
the tumbler hard. The thermocol ball gets displaced. Now we hit the tumbler gently,
this time thermocol ball gets displaced a little.
The displacement of the ball is a measure of the amplitude of the vibration
of the tumbler.
Amplitude is larger in the first case
The loudness of sound depends on its amplitude. When the amplitude of the vibration is large, the sound produced is loud. When the amplitude is small, the sound produced is feeble.
Conclusion
The loudness of sound depends upon the amplitude of vibrations
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