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NCERT Solutions for Class 8 Science Chapter 10 Sound will assist you in scoring more marks. This includes the textbook and their solutions for Sound Chapter 10 of Class 8 Science, which is made in adherence to the updated syllabus 2023 released by CBSE.
Our solutions offer ample material to help students build a strong foundation and improve their understanding of the subject.
On this page, you will find all the NCERT Solutions for Class 8 Science Chapter 10 Sound which includes detailed exercise-based solutions. These NCERT Solutions for Class 8 Science are downloadable and easy to access. Our Science experts have meticulously developed these NCERT Solutions for Class 8 to support students in preparing for their Class 8 exams.
NCERT Solutions for Class 8 Science Chapter 10 Sound
Sound Class 8 Science NCERT Textbook Questions
Exercise Questions
1. Choose the correct answer.
Sound can travel through
(a) gases only (b) solids only
(c) liquids only (d) solids, liquids and gases.
Solution: (d) solids, liquids and gases
2. Voice of which of the following is likely to have minimum frequency?
(a) Baby girl (b) Baby boy
(c) A man (d) A woman
Solution: (c) A man
3. In the following statements, tick ‘T’ against those which are true, and ‘F’ against those which are false.
(a) Sound cannot travel in vacuum. (T/F)
(b) The number of oscillations per second of a vibrating object is called its time period. (T/F)
(c) If the amplitude of vibration is large, sound is feeble. (T/F)
(d) For human ears, the audible range is 20 Hz to 20,000 Hz. (T/F)
(e) The lower the frequency of vibration, the higher is the pitch. (T/F)
(f) Unwanted or unpleasant sound is termed as music. (T/F)
(g) Noise pollution may cause partial hearing impairment. (T/F)
Solution:
(a) True
(b) False
(c) False
(d) True
(e) False
(f) False
(g) True
4. Fill in the blanks with suitable words.
(a) Time taken by an object to complete one oscillation is called _____________.
(b) Loudness is determined by the _____________ of vibration.
(c) The unit of frequency is ______________.
(d) Unwanted sound is called _______________ .
(e) Shrillness of a sound is determined by the _________________ of vibration.
Solution:
(a) Time taken by an object to complete one oscillation is called Time period.
(b) Loudness is determined by the amplitude of vibration.
(c) The unit of frequency is Hertz (Hz).
(d) Unwanted sound is called Noise .
(e) Shrillness of a sound is determined by the Frequency of vibration.
5. A pendulum oscillates 40 times in 4 seconds. Find its time period and frequency.
Solution:
Time Period = Time Taken / No. of Oscillations
= 4/40
= 0.1 seconds
Frequency = No of Oscillations / Time taken
= 40/4
= 10 Hertz
Therefore, Frequency = 10 Hertz and Time period = 0.1 seconds.
6. 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 the vibration?
Solution:
Here, time taken = 1 second
No of Oscillations = 500
Time Period = Time Taken / No. of Oscillations
= 1/ 500
= 0.002 seconds
7. Identify the part which vibrates to produce sound in the following instruments.
(a) Dholak
(b) Sitar
(c) Flute
Solution:
(a) Dholak – Dholak has a Streched Membrane which vibrates to produce sound.
(b) Sitar – When the Streched String in sitar vibrates, they produce sound.
(c) Flute – Air Column present in flute produces sound.
8. What is the difference between noise and music? Can music become noise sometimes?
Solution:
Noise is an unwanted or unpleasant sound, whereas music produces a pleasant sensation. Yes, music can become noise when its too loud and crosses the bearable range of sound of our ears.
9. List sources of noise pollution in your surroundings.
Solution:
Major Sources of noise pollution are as follows-
– Honking of horms
– Use of kitchen appliances
– Sound of vehicles
– Sound of machinery in factories
– Sound of television
– Sound of loud music at parties and weddings
– Bursting of crackers
– Use of coolers etc
10. Explain in what way noise pollution is harmful to human.
Solution:
Harmful effects of noise pollution are as follows-
(i) Person who is exposed to loud sound continuously may get temporary or permanent impairement of hearing.
(ii) Many health disorders like anxiety, hypertension, lack of sleep might also occur due to noise pollution or loud music.
(iii) Can also cause mental illness.
11. Your parents are going to buy a house. They have been offered one on the roadside and another three lanes away from the roadside. Which house would you suggest your parents should buy? Explain your answer.
Solution:
I would suggest my parents to get the house which is three lanes away from the roadside because if it will be closer to the road, there will be continuous sound of vehicles and it will disturb our peace of mind due to noise pollution. Therefore, the house that is three lanes away will be much more peaceful to live.
12. Sketch larynx and explain its function in your own words.
Solution:
The larynx, often referred to as the voice box, is situated at the upper part of the windpipe. Two vocal cords are stretched across the voice box or larynx in such a way that it leaves a narrow slit between them for passage of air. When air from the lungs is pushed through this gap, the vocal cords vibrate, generating sound. Muscles attached to the vocal cords can make the cords tight or loose. When the vocal cords are tight and thin, the type or quality of voice is different from that when they are loose and thick.
13. 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 why?
Solution:
The speed of light is more than that of sound. Due to more speed, the light reaches us before the sound does. So lightening is seen earlier and thunder is heard later.
Summary
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