Chhattisgarh State Board Class 8 Science Chapter 10 Sound Exercise Multiple Choice,, Questions and Answers here.
Choose correct answer out of the choice gives-
1.) The range of audible frequencies for human beings is-
a) 0-20 hertz
b) 20- 200 hertz
c) 0- 20,000 hertz
d) 20-20,000 hertz
Ans-d) 20 to 20,000 hertz
2.) On increasing the frequency of a sound ,what else increases –
a) Its pitch
b) Its intensity
c) Its time period
d) Its amplitude
Ans-a) its Pitch
3.) To hear the echo clearly, the minimum distance of the reflecting surface should be-
a) 11 metre
b) 34 metre
c) 17 metre
d) 50 metre
Ans-c) 17 metre
4.) Sound propagation is not possible-
a) In metals
b) In water
c) In vacuum
d) In air
Ans- c) in vacuum
Write the definations of amplitude and frequency.
Ans-Amplitude-the maximum displacement of the vibrating object from its mean position is called the Amplitude.
Frequency- The number of oscillations in one second is the frequency of oscillation. Frequency is measured in oscillation per second or in hertz.
3.) How would you show through an experimental that sound can propagate in gases?
Ans-form the bell-jar experiment we can show fro propagation of sound medium is necessary. In this experiment hydrophone instruments is used.
Now when we placed an electrical bell connected to a battery in an air tight bell jar, on ringing the bell sound could be heard as the jar is fill with air.
Then the air in the jar is evecuted with the help of suction pump so we can not heard any sound when the bell is reining . from this experiment we can understand that sound can propagate in gas also.
4.) Differentiate between a noise and a melodious sound.
Melodious sounds | Noise |
The sound which is pleasant to our ears is called melodious sound | The sound which is not pleasant to our ears is called a noise. |
Harmonious vibrations that have a fixed relationship whit each other produces melodious sound. | Non- harmonious vibrations produce noise. |
For example- the musical instruments like sitar, veena, violin etc | For example- the sound of bullet, the sound of crackers etc. |
5.) Sound is heard clearly in a big room with curtains on its walls rather in a room without curtains why?
Ans-sounds is heard clearly in a big room with curtains on its walls because curtains are good absorbers and they absorbs the sound which produces In a room and they also stop the reflection of sound and echo is not heard therefore sound is heard clearly with curtains in room wall.