CLASS 8 MODEL QUESTIONS AND ANSWERS | PHYSICS

CLASS 8 PHYSICS

1. Pitch, depends on the …………..of sound. 
2. …………..is the measure of audibility of a person.
3. The sharpness of the sound heard is the……..
4. Why do the astronauts use radio devices to

communicate with one another?

5. Human beings Limits of Audibility.
6. Frequency of infrasonic sound. 
7. Production of sound in a manner unhealthy

to human being is noise pollution.

Write any two way to reduce noise pollution?

8. Production of sound in a manner unhealthy

to human being is noise pollution.

Write any four way to reduce noise pollution?

9. Write the reason.

The sound of the Galton whistle used to call dogs cannot be heard by human beings.

10. The frequency  of sound  produced when a table is struck is 250 Hz.
11. a) What is the natural frequency of table?
12. b) Write any two factors that influence the natural frequency.

 

ANSWERS

 

1. Frequency
2. Loudness 
3. Pitch
4. Because there is no medium
5. 20 Hz – 20 kHz
6. Below 20 Hz
7. *  Ensure that silencers in vehicles work properly.

* Plant as many trees as possible to minimise noise pollution. Trees can reduce loudness of sound by absorbing sound energy

8• Use of air horns in vehicles is prohibited by law.

• Box type loudspeakers must be used in place of horn type loud speakers.
• Ensure that silencers in vehicles work properly.
• Plant as many trees as possible to minimise noise pollution. Trees can reduce loudness of sound by absorbing sound energy.

9. The frequency of sound produced from a Galton whistle is about 30000 Hz.Human beings cannot hear  above 20,000 Hz

10 a) 250 Hz

1. b)  Nature

 Cross sectional area

 Stretching

 Length

 Thickness