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प्रश्न
A vibrating tuning fork is placed over the mouth of a burette filled with water. The tap is opened and the water level gradually falls. It is observed that the sound becomes the loudest for a particular length of the air column. What is the name of the phenomenon taking place when this happens? Why does the sound become the loudest?
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उत्तर
Resonance in the air column. The frequency of vibrating tuning fork becomes equal to the frequency of vibrating air column. As a result, the amplitude of the sound produced increases. Since loudness is proportional to the square of the amplitude, so the sound is loudest.
संबंधित प्रश्न
What are forced vibrations?
Give one example to illustrate forced vibrations.
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When a body vibrates under a periodic force, the vibrations of the body are ______.
(i) Define resonant vibrations.
(ii) Which characteristic of sound, makes it possible to recognize a person by his voice without seeing him?
In fig. , P, Q, R and S represent test tubes each of height 20 cm which are filled with water upto heights of 10 cm, 14 cm, 16 cm and 18 cm respectively. If a vibrating tuning fork is placed over the mouth of test tube Q, a loud sound is heard.
(i) Describe the observations with the tubes P, R and S.
(ii) Give the reason for your observation in each case.
(iii) State the principle illustrated by the above experiment.
In Fig. A, B, C and D are four pendulums suspended from the same elastic string XY. The lengths of pendulum A and D are equal, while the length of pendulum B is shorter and of the pendulum C is longer. Pendulum A is set into vibrations.
- What is your observation about the vibrations of pendulum D?
- Give reason for your observation in part (a).
- What type of vibrations take place in pendulums Band C?
- Give reason for the answer in part (c).
Give two examples of forced vibrations.
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