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प्रश्न
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उत्तर
Bats make a series of twittering sound, so high pitched that human ear can not hear. These sound waves strike against the obstacles less in their path of flight and send back echoes to the bat’s ear. The echoes tell the bats, how they must turn in the air to avoid colliding with the obstacles or with one another.
संबंधित प्रश्न
Calculate the wavelength of a sound wave whose frequency is 220 Hz and speed is 440 m/s in a given medium.
Write true or false for a given statement.
The frequency is measured in hertz.
Name the characteristic which differentiates two sounds of the same pitch and same loudness.
How does the frequency of sound given by a stretched string depend on its
- length,
- tension?
What is sound? How is it produced?
What is a transverse wave? In which medium: solid, liquid or gas, can it be produced?
What is sound? What causes it to produce?
Match the pairs.
| Group ‘A’ | Group ‘B’ |
| (a) Flute | (1) Frequency less than 20 Hz |
| (b) Frequency | (2) Frequency more than 20000 Hz |
| (c) Sound level | (3) Vibrations in the air |
| (d) Ultrasonic sound | (4) Measured in Hz |
| (e) Infrasonic sound | (5) Decibel |
A continuous disturbance is created on the surface of water in a ripple tank with a small piece of cork floating on it. Describe the motion of the cork. What does the motion of the cork tell about the disturbance?
The diagram given below shows a displacement distance graph of a wave. If the velocity of wave is 160 ms-1, calculate:
- wavelength
- frequency
- amplitude.
State the effect of pressure on the speed of sound in air.
What cause sound? Why do we require a material medium for the transmission of sound?
Explain how the principle of echo is used by
The bat during its flight at night
A sound wave travels 2000 m in 8 s. What is the velocity of the sound?
A musical instrument is producing continuous note. This note cannot be heard by a person having a normal hearing range. This note must then be passing through ______.
Describe with diagram, how compressions and rarefactions are produced.
The sound produced by a thunderstorm is heard 10 s after the lightning is seen. Calculate the approximate distance of the thunder cloud. (Given the speed of sound = 340 m s–1.)
Give scientific reasons.
In earlier times, people used to listen for the arrival of a distant train by putting their ear to the rail.
