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प्रश्न
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उत्तर
Sounds can be roughly divided into two categories: (i) music, and (ii) noise.
Regularity, contrivity and rapidity make musical sounds different from a noise. The distinction between music and noise is not very sharp; it is subjective.
| Music | Noise |
| 1. It is pleasant, smooth and agreeable to the ear. | 1. It is harsh, discordant and displeasing to the ear. |
| 2. It is produced by the vibrations which are periodic. | 2. It is produced by an irregular succession of disturbances. |
| 3. All the component waves are similar without any sudden change in their wavelength and amplitude | 3. The component wave chanqes their character suddenly and they are of short duration.. |
| 4. The sound level is low (below 30 dB). | 4. The sound level is hiah (above 120 dB). |
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संबंधित प्रश्न
How does the medium affect the amplitude of free/natural vibrations of a body?
When a troop crosses a suspension bridge, the soldiers are asked to break steps. Explain the reason.
Why are the stringed instruments like guitar provided with a hollow sound box?
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).
Explain why stringed musical instruments, like the guitar, are provided with a hollow box.
State two ways in which resonance differs from forced vibrations.
Explain why are soldiers asked to walk out of step while crossing bridges?
What are the factors that affect the frequency of a vibrating string and how do they affect the frequency?
What do you understand by free vibrations of a body? Draw a displacement-time graph to represent them. Given one example.
