Advertisements
Advertisements
प्रश्न
Advertisements
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.
APPEARS IN
संबंधित प्रश्न
Calculate the wavelength of a sound wave whose frequency is 220 Hz and speed is 440 m/s in a given medium.
The frequency of a source of sound is 100 Hz. How many times does it vibrate in a minute?
Select the correct alternative :
We can hear sound of frequency
Name the two characteristics of sound which differentiate two sounds from each other.
State the factors on which the pitch of a sound depends.
Differentiate between a high pitch sound and a low pitch sound.
What are wavelength, frequency, time period and amplitude of a sound wave?
At 20°C, the minimum distance of a person from a sound reflecting surface to hear an echo is :
Fig. shows three ways in which a string of length l in an instrument can vibrate.
 |
 |
 |
| (i) | (ii) | (iii) |
- Which of the diagram shows the principle note?
- Which vibration has the frequency four times that of the first?
- Which vibration is of the longest wavelength?
- What is the ratio of the frequency of the vibration in (i) and (ii)?
How does the frequency of sound given by a stretched string depend on its
- length,
- tension?
How is sound perceived by us?
A medium is necessary for ______ of sound.
The distance between three consecutive crests of wave is 60 cm. If the waves are produced at the rate of 180/ min, calculate:
- wavelength
- time period
- wave velocity.
he sound of an explosion on the surface of a lake is heard by a boatman 120 m away and by a diver 120 m below the point of explosion. Out of the two persons, who would hear the sound first? Why?
A person hearing at one end of a long metal bar hears two distinct sounds when the other end is struck with a stone. Explain, giving scientific reasons
The amplitude of the sound wave decides its
Match the following.
| 1. | Tuning fork | The point where density of air is maximum |
| 2. | Sound | Maximum displacement from the equilibrium position. |
| 3. | Compressions | The sound whose frequency is greater than 20,000 Hz. |
| 4. | Amplitude | Longitudinal wave. |
| 5. | Ultasonics | Production of sound. |
Mention two cases in which there is no Doppler effect in sound?
______ is an unwanted sound.
Two sound waves X and Y have the same amplitude and the same wave pattern but their frequencies are 60 Hz and 120 Hz respectively, then ______.
