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प्रश्न
What do you understand by forced vibrations?
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उत्तर
Sometimes to keep a body vibrating, a periodic force is applied to it. In such a case, the body does not vibrate with its own natural frequency but gradually starts vibrating with the frequency of the applied periodic force. Such vibrations produced in a body are called forced vibrations, e.g., in a string of musical instruments, when the vibrations producing a loud sound.
संबंधित प्रश्न
In the diagram below, A, B, C, D are four pendulums suspended from the same elastic string PQ. The length of A and C are equal to each other while the length of pendulum B is smaller than that of D. Pendulum A is set into a mode of vibrations
1) Name the type of vibrations taking place in pendulums B and D?
2) What is the state of pendulum C?
3) State the reason for the type of vibrations in pendulum B and C.
Give one example to illustrate forced vibrations.
In following figure shows two tuning forks A and B of the same frequency mounted on two separate sound boxes with their open ends facing each other. The fork A is set into vibration.
- Describe your observation.
- State the principle illustrated by this experiment.
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.
Name the phenomenon involved in tuning your radio set to a particular station and define it.
(i) Define resonant vibrations.
(ii) Which characteristic of sound, makes it possible to recognize a person by his voice without seeing him?
When acoustic resonance takes place, a loud sound is heard. Why does this happen? Explain.
Explain a person walking past a railway line, in the middle of night hears a ringing sound along with the sound of his footsteps.
