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प्रश्न
Name the type of waves that are used for sound ranging. Why are radio waves not audible to us?
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उत्तर
Radio waves. These waves are not audible to us because their frequency is 3 × 104 Hz to 3 × 109 Hz. Which is more than the audible range.
संबंधित प्रश्न
Define amplitude term in relation to a wave.
What is a megaphone ? Name the principle on which a megaphone works.
Write the approximate value of the speed of sound in water.
What is meant by echo depth sounding?
Waves produced on the surface of the water are formed to move with a velocity of 24 ms−1. If the wavelength of these waves equals 20 cm. find the
(i) frequency (no. of waves produced per second)
(ii) the time period (i.e. the time required to produce one wave) for these waves.
(i) A man stands at a distance of 68 m from a cliff and fires a gun. After what time interval will he hear the echo, if the speed of sound in air is 340 ms−1?
(ii) If the man had been standing at a distance of 12 m from the cliff would he have heard a clear echo?
What is meant by an echo? Explain.
Match the following:
| 1. | Stethoscope | a. | Repeated reflections |
| 2. | Echogram | b. | Multiple reflections |
| 3. | SONAR | c. | Ultrasonic waves |
| 4. | Reverberation | d. | Speed of underwater objects |
