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प्रश्न
Differentiate between the following:
Free and forced vibrations.
उत्तर
| Free vibrations | Farced vibrations |
| 1. When a body vibrates with its natural frequency and ti me period which is characteristic of the body itself, it is said to have free vibrations. | 1. When a body is set into vibrations with the help of a strong periodic force then the vibration is said to be forced vibration. The frequency of such vibrations may not be equal to the natural frequency of the body. |
| 2. It is difficult to realize such vibrations in practice. They can take place only in vacuum. | 2. Such vibrations can be realized in practice. |
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संबंधित प्रश्न
Resonance is a special case of ______ vibrations, when frequency of the driving force is ______ natural frequency of the body.
A tuning fork of frequency 256 Hz will resonate with another tuning fork of frequency:
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.
The diagram below shows three different modes of vibration P, Q and R of the same string of a given length.
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| P | Q | R |
- Which vibration will produce a louder sound and why?
- Which vibration will produce sound of maximum shrillness (or pitch) and why?
- What is the ratio of wavelength of vibrations P and R?
Explain a tuning fork (vibrating) is held close to ear. One hears a faint sound. The same vibrating tuning fork is placed on table, such that its handle is in contact with table, one hears a loud sound.
Explain a person walking past a railway line, in the middle of night hears a ringing sound along with the sound of his footsteps.
Explain Why are stringed musical instruments provided with large sound boxes?
What do you understand by forced vibrations?
What do you understand by free vibrations of a body? Draw a displacement-time graph to represent them. Given one example.
