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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 lengths 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.

- Name the type of vibrations taking place in pendulums B and D.
- What is the state of pendulum C?
- State the reason for the type of vibrations in pendulums B and C.
How does the medium affect the amplitude of free/natural vibrations of a body?
Distinguish between the free (or natural) and 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.
When a troop crosses a suspension bridge, the soldiers are asked to break steps. Explain the reason.
How do you tune your radio set to a particular station ? Name the phenomenon involved in doing so and define it.
Differentiate between the following:
Free and forced vibrations.
Explain free and forced vibrations. Give an experimental arrangement to illustrate the phenomenon of resonance.
