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प्रश्न
Explain how is the principle of echo used by
(a) The bat during its flight at night,
(b) The dolphin to locate small fish as its prey.
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उत्तर
(a) Bats can produce and detect the sound of very high frequency. The bats fly with speed much lower than the speed of sound. The sounds produced by flying bats get reflected from any obstacle in front of it. By hearing the echoes, bats come to know where the obstacles are, even in the dark. So, they can fly safely without colliding with the obstacles. This process of detecting obstacles is called sound ranging.
(b) Dolphins detect their enemies and small fishes by emitting ultrasonic waves in all directions and then hearing their reflected sound i.e. echo. Dolphins can judge the nature of obstacles or of small fish by hearing the echo and catch their prey.
संबंधित प्रश्न
A certain sound has a frequency of 256 hertz and a wavelength of 1.3 m.
1) Calculate the speed with which this sound travels
2) What difference would be felt by a listener between the above sound and another sound traveling at the same speed, but of wavelength 2.6 m?
A wave passes from one medium to another medium. Mention one property of the wave out of speed, frequency or wavelength which changes.
State two factors on which the speed of a wave travelling in a medium depends.
State two differences between the light and sound waves.
State the use of echo by a bat, dolphin and fisherman.
A type of electromagnetic wave has a wavelength of 50 Å. Name the wave and state one use of this type of wave.
Draw a diagram representing a wave of amplitude 4 cm and wavelength 2 m. If the frequency of the wave is 150 Hz, calculate its velocity.
A sound wavelength of 0.332 m has a time period of 10−3 s. If the time period is decreased to 10−4 s, calculate the wavelength and frequency of the new wave.
