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Question 1

What is the difference between noise and music? Can music become noise sometimes?

Unpleasant sounds are called noise whereas music is a sound is one which produces pleasing sensation. But, if the musical sound is too loud, it becomes noise.



Following are the major source of noise pollution:
  • Sounds of vehicles. 
  • Sounds of bursting of crackers and explosives. 
  • Sounds of loudspeaker, TVs, transistors. 
  • Sounds of kitchen appliances. 
  • Sounds of desert coolers, air conditioners etc.

Question 3

Explain in what way noise pollution is harmful to humans.

Presence of excessive noise in the surroundings may cause many health related problems e.g.,
  • Lack of sleep
  • Hypertension
  • Anxiety etc.

Question 4

Your parents are going to buy a house. They have been offered one on the roadside and another three lanes away from he roadside. Which house would you suggest your parents should buy? Explain your answer.

I will suggest our parent to buy the house which is three lanes away from the roadside. This is because the house on the roadside will receive the unwanted sounds of vehicles whereas the house which is three lanes away from the roadsides will be free from noise pollution.

Question 5

Explain the function of larynx in your own words.

In humans, the sound is produced by the voice box or the larynx. It is situated in the throat. Below it is the wind pipe. The two vocal cords, are stretched across the voice box or larynx in such away that it leaves a narrow slit between them for the passage of air when the lungs force air through the slit, the vocal cords vibrate producing sound.


Question 6

Lightning and thunder take place in the sky at the same time and at the same distance from us. Lightning is seen earlier and thunder is heard later. Can you explain?

light travels at the speed of 3 × 108 m/s while sound travels at a speed of 332 m/s i.e., light travels much faster than sound that is way lightning is seen earlier and thunder is heard later.


Question 7

A pendulum oscillates 40 times in four seconds. Find its time period and frequency.


Frequency f =

The time period =

Question 8

The sound from a mosquito is produced when it vibrates its wings at an average rate of 500 vibrations per second. What is the time period of vibration?


Frequency = 500 vibrations/second

Time period = .

Question 9

Identify the part which vibrates to produce sound in the following instruments.


(i) Dholak

(ii) Sitar

(iii) Flute

  • Dholak – Animal skin
  • Sitar – String
  • Flute - Wind

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