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Ever wondered how we know a train is coming, or when our phone rings or the cooker whistles? That’s all because of sound! Class 8 Science Chapter 10 Sound explains how sound is produced, how it travels, and how we hear it. The NCERT Solutions for Class 8 Science Chapter 10 are created by expert faculty based on latest NCERT Syllabus.
NCERT Solutions for Class 8 Science Chapter 10 Sound are provided here to help students clearly understand how sound is produced, travels, and is heard. These NCERT solutions include answers all exercise questions, important concepts, and step by step explanations to simplify problem solving. By covering all major topics like vibrations, pitch, frequency, and propagation of sound, these solutions not only prepare students well for school exams but also build a strong base for future studies in science. In these NCERT Solutions for Class 8 Science, we are also providing the Approach to solve the Chapter 10 Questions to help students learn how to tackle different types of problems.
You can download the NCERT Solutions for Chapter 10 Sound in PDF format to study anytime, anywhere. This downloadable PDF includes solved exercise questions with detailed solutions.
Q1. Choose the correct answer.
Sound can travel through
(a) gases only (b) solids only (c) liquids only (d) solids, liquids and gases.
Answer:
Sound can travel through solids, liquids and gases. But the sound does not travel in a vacuum
(d) is correct.
Choose the correct answer.
Q2. Voice of which of the following is likely to have minimum frequency?
(a) Baby girl (b) Baby boy (c) A man (d) A woman
Answer:
Voice of a man would have the lowest frequency since it is of a lower pitch than the voice of a woman, a baby boy and a baby girl. Pitch is proportional to frequency.
(c) is correct
(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)
Answer:
(a) T .
Sound cannot travel in a vacuum as it requires a medium to travel.
(b) F .
The number of oscillations per second of a vibrating object is called its frequency. Time period is the time taken to complete one oscillation.
(c) F .
The sound of a vibration is directly proportional to the square of the amplitude of vibration , therefore, the sound will be feeble if the amplitude of vibration is low.
(d) T .
For humans, the audible range of frequency is 20 Hz to 20,000 Hz.
(e) F .
The pitch of a sound is directly proportional to its frequency.
(f) F .
Unwanted or unpleasant sound is termed as noise.
(g) T .
Exposure to loud noise for a long period of time may cause partial hearing impairment.
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.
Answer:
(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 .
(d) Unwanted sound is called noise .
(e) Shrillness of a sound is determined by the frequency of vibration.
Q5. A pendulum oscillates 40 times in 4 seconds. Find its time period and frequency.
Answer:
Time Period is defined as the time taken to complete one oscillation.
Time taken to complete 40 oscillations
Time taken to complete 1 oscillation
Frequency is defined as the number of oscillations per second.
Number of oscillations in 4 seconds
Number of oscillations in 1 second
Frequency
Answer:
The time period of vibration is defined as the time taken to complete one oscillation.
The time period of vibration is defined as the time taken to complete one oscillation.
Time taken to complete 500 vibrations
Time taken to complete 1 vibration
Time period
Answer:
(a) The stretched membrane over the body of the dholak vibrates to produce sound.
(b) The strings stretched over the body of the sitar vibrate to produce sound.
(c) The air inside the flute vibrates when air is blown into it to produce sound.
Q8 . What is the difference between noise and music? Can music become noise sometimes?
Answer:
Noise is sound which is irritating and unpleasant whereas music is sound which is pleasant and soothing. Music can turn into noise at very high volume.
Q9 . List sources of noise pollution in your surroundings.
Answer:
Sources of noise pollution in our surroundings are:
(a) Horns of vehicles on the road.
(b) Loudspeakers and radios.
(c) Crackers.
(d) Machinery inside factories and appliances at homes.
(e) The noise produced by a large number of people.
Q10 . Explain in what way noise pollution is harmful to human.
Answer:
Noise pollution can cause several health-related problems such as:
(i) Insomnia.
(ii) Anxiety and stress.
(iii) Hearing impairment
(iv) Headaches.
Answer:
I would suggest them to buy the one three lanes away from the roadside as there will be less noise pollution caused by vehicles moving on the road.
Q12 . Sketch larynx and explain its function in your own words.
Answer:
Inside the larynx, there are two vocal cords with a gap between them and when air passes through this gap the vocal cords vibrate and as we know the sound is produced when something vibrates, therefore, this vibration of vocal cords inside the larynx produce sound.
Answer:
The speed of light is much faster than the speed of sound, due to this the light emitted by lightning reaches our eyes before the sound of thunder reaches our ears and we see lightning before we hear thunder.
Below are the important topics covered in Class 8 NCERT Science Chapter 10 Sound. These topics will help you understand how sound is produced, travels, and is heard.
10.1 Sound is Produced by a Vibrating Body
10.2 Sound Produced by Humans
10.3 Sound Needs a Medium for Propagation
10.4 We Hear Sound through Our Ears
10.5 Amplitude, Time Period and Frequency of a Vibration
10.6 Audible and Inaudible Sounds
10.7 Noise and Music
10.8 Noise Pollution
Below are the important formulas from Class 8 Science Chapter 10 Sound. These formulas will help you solve numerical problems accurately and improve your understanding of how sound behaves.
Where,
Where,
To solve questions from Class 8 Science Chapter 10: Sound start by understanding what the question is asking whether it is about sound frequency, or the speed of sound. Identify the given data like frequency, time period, or wavelength. Use appropriate formulas such as Speed
The chapter-wise NCERT solutions for all the science chapters are listed here along with their links:
Frequency is number of cycles per second. Frequency is measured in Hz. 1Hz = 1 cycle/sec
The vibration of vocal cords inside the larynx produce sound
Pitch is proportional to frequency.
Topics of sound class 8 are given below:
10.1 Sound is Produced by a Vibrating Body
10.2 Sound Produced by Humans
10.3 Sound Needs a Medium for Propagation
10.4 We Hear Sound through Our Ears
10.5 Amplitude, Time Period and Frequency of a Vibration
10.6 Audible and Inaudible Sounds
10.7 Noise and Music
10.8 Noise Pollution
Sound is a form of energy that travels through a medium via vibrations, and can be heard by human ears when sound waves cause vibrations in the eardrum.
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