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प्रश्न
Differentiate between the following:
Free and forced vibrations.
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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
What are mechanical waves?
The adjacent diagram shows three different modes of vibrations P, Q and R of the same string.
(i) Which vibration will produce a louder sound and why?
(ii) The sound of which string will have maximum shrillness?
(iii) State the ratio of wavelengths of P and R.
The diagram above shows a wire stretched over a sonometer. Stems of two vibrating tuning forks A and Bare touched to the wooden box of the sonometer. It is observed that the paper rider (a small piece of paper folded at the centre) present on the wire flies off when the stem of vibrating tuning fork B is touched to the wooden box but the paper just vibrates when the stem of vibrating tuning fork A is touched to the wooden box.
1) Name the phenomenon when the paper rider just vibrates.
2) Name the phenomenon when the paper rider flies off.
3) Why does the paper rider fly off when the stem of tuning fork B is touched to the box?
Give one example to illustrate forced vibrations.
In following figure shows A, B , C and D represent test tube each of height 20 cm which are filled with water up to heights of 12 cm, 14 cm, 16cm and 18cm respectively. If a vibrating tuning fork is placed over the mouth if test tube D, a loud sound is heard.
- Describe the observations with the tubes A, B and C when the vibrating tuning fork is placed over the mouth of these tubes.
- Give the reason for your observation in each case.
- State the principle illustrated by the above experiment.
A tuning fork of frequency 256 Hz will resonate with another tuning fork of frequency:
When a tuning fork, struck by a rubber pad, is held over a length of the air column in a tube, it produces a loud sound for a fixed length of the air column. Name the above phenomenon. How does the frequency of the loud sound compare with that of the tuning fork? State the unit for measuring loudness.
Explain a person walking past a railway line, in the middle of night hears a ringing sound along with the sound of his footsteps.
What are the factors that affect the frequency of a vibrating string and how do they affect the frequency?
