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प्रश्न
Give a scientific reason.
We can hear the movement of a mosquito’s wings but we cannot hear the movement of our hands.
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उत्तर
The frequency of the sound produced by the movement of a mosquito’s wings lies within the human audible range (20 Hz to 20,000 Hz), whereas the sound produced by the movement of our hands has a frequency below 20 Hz, which is inaudible to humans. Therefore, we can hear the movement of a mosquito's wings but not that of our hands.
संबंधित प्रश्न
A person is standing at the seashore. An observer on the ship which is anchored in between a vertical cliff and the person on the shore fires a gun. The person on the shore hears two sounds, 2 seconds and 3 seconds after seeing the smoke of the fired gun. If the speed of sound in the air is 320 ms-1 then calculate:
1) the distance between the observer on the ship and the person on the shore.
2) the distance between the cliff and the observer on the ship.

When sound travels in form of a wave
What is longitudinal wave?
Name the characteristic of sound related to its frequency
Two waves of the same pitch have amplitudes in the ratio 1:3. What will be the ratio of frequencies?
Name the unit in which loudness of sound is measured.
Name musical instrument, one in each case, which produces its notes by using the following. In each case state the method used to produce notes of different pitches and loudness.
(a) A vibrating string.
(b) A vibrating column air.
(c) Vibration of any other body.
Name the subjective property of light related to its wavelength.
Name one main factor on which each character such as intensity, pitch, and quality of musical sound depends.
A 0.6 m long stretched wire is made to vibrate in two different modes as shown in figure
(a)

(b)

(i) If the frequency of the note produced in (b) is n, what is the frequency in case (a)?
(ii) In which case (a) or (b), is the note louder? Give reasons.
(iii) In which case is the pitch higher? Give reason.
