NCERT Solutions For Class 8 Science Chapter 13 Sound

Edited By Vishal kumar | Updated on Sep 15, 2023 08:33 AM IST

NCERT Solutions Class 8 Science Chapter 13 – Access and Download Free PDF

NCERT Solutions for Class 8 Science Chapter 13 Sound: Welcome to the updated sound class 8 NCERT solutions. On this Careers360 page, you will find comprehensive NCERT Solution meticulously crafted by experts. Each step is explained in detail. The solutions for Chapter 13 of Class 8 Science comprise a total of thirteen questions, including multiple-choice questions, true/false statements, fill-in-the-blanks, and subjective-type questions. Our team at Careers360 has designed these answers in a step-by-step and easy-to-understand language. The PDF version of the solutions is also available for download, allowing students to utilize them at their convenience.

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NCERT Solutions Class 8 Science Chapter 13 – Access and Download Free PDF
NCERT Solutions for Class 8 Science Chapter 13 Sound
NCERT solutions for class 8 science chapter 13 sound: Solved Exercise Questions
NCERT Solutions For Class 8: Subject Wise
NCERT Solutions for Class 8 Science Chapter 13 Sound
NCERT solutions for class 8 science chapter 13 Sound: Points to remember
Key features of sound Class 8 questions and answers

NCERT Solutions For Class 8 Science Chapter 13 Sound

Solution for Sound Chapter Class 8 is part of NCERT Solutions for Class 8 Science. In day-to-day life, you hear a variety of sounds. Have you ever thought about how sounds are produced? What makes male and female voices so different from each other? You will get the know answers to these questions in solutions of NCERT class 8 science chapter 13 sound. After studying the chapter attempt NCERT exercise of science chapter 13. For better preparation CBSE NCERT solutions for class 8 science chapter 13 sound are helpful.

You must have observed that when we take a steel bucket and hit it with a small hammer, vibrations are caused. These vibrations are responsible for the production of sound. Production of sound in humans is mainly due to the presence of a voice box or larynx. It is found to be present at the upper end of the windpipe. You will understand the structure of the voice box and the mechanism of production of sound by the voice box after studying this chapter. The class 8 science chapter 13 question answer helps students in solving homework problems. The NCERT solutions for class 8 science chapter 13 sound give an explanation to 13 exercise questions.

**According to the CBSE Syllabus for the academic year 2023-24, this particular chapter has been assigned a new chapter number, which is Chapter 9.

Free download class 8 science chapter 13 NCERT solutions PDF for CBSE exam.

NCERT Solutions for Class 8 Science Chapter 13 Sound

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NCERT solutions for class 8 science chapter 13 sound: Solved Exercise Questions

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.

Q3. 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)

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.

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.

$\\Time \ taken \ to \ complete \ 40 \ oscillations\ = 4 \ seconds\\ Time \ taken \ to \ complete \ 1 \ oscillation\ = \ \frac{4}{40}\ seconds\ = \ 0.1 \ second\\$

Frequency is defined as the number of oscillations per second.

$\\Number \ of \ oscillations \ in \ 4 \ seconds \ = \ 40 \\ Number \ of \ oscillations \ in \ 1 \ second \ = \ \frac{40}{4} \ = \ 10\\ Frequency \ = \ 10 \ Hertz.$

Q6 . 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?

Answer:

The time period of vibration is defined as the time taken to complete one oscillation.

$\\Time \ taken \ to \ complete \ 500 \ vibrations \ = \ 1 \ second.\\ Time \ taken \ to \ complete \ 1 \ vibration = \frac{1}{500} \ second \ = \ 0.002\ seconds.\\ Time \ period \ = \ 0.002 \ seconds.$

Time Period = 0.002 s.

Q7 . Identify the part which vibrates to produce sound in the following instruments.
(a) Dholak (b) Sitar (c) Flute

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.

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.

(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.

Q11 . 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.

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:

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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.

Q13 . 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?

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.

The solution for class 8 chapter 13 science consists of a total of thirteen questions that are a mix of multiple-choice questions, true/false statements, fill in the blanks, and subjective type questions. The experts at Careers360 have created the Class 8 Science Chapter 13 question answers in a step-by-step and easy-to-understand language. The PDF version of the solutions is also available for download, and students can use them according to their convenience.

NCERT Solutions For Class 8 Science- Chapter-wise

Chapter 1	Crop Production and Management
Chapter 2	Microorganisms Friend and Foe In Microorganisms
Chapter 3	Fibres and Plastics
Chapter 4	Materials Metals and Non Metals
Chapter 5	Coal and Petroleum
Chapter 6	Combustion and Flame
Chapter 7	Conservation of Plants and Animals
Chapter 8	Cell Structure and Functions
Chapter 9	Reproduction in Animals
Chapter 10	Reaching the Age of Adolescence
Chapter 11	Force and Pressure
Chapter 12	Friction
Chapter 13	Sound
Chapter 14	Chemical Effects of Electric Current
Chapter 15	Some Natural Phenomena
Chapter 16	Light
Chapter 17	Stars and the Solar System
Chapter 18	Pollution of Air and Water

NCERT Solutions For Class 8: Subject Wise

NCERT Solutions for Class 8 Science Chapter 13 Sound

Subtopics of sound class 8 are given below:

13.1 Sound is Produced by a Vibrating Body

13.2 Sound Produced by Humans

13.3 Sound Needs a Medium for Propagation

13.4 We Hear Sound through Our Ears

13.5 Amplitude, Time Period and Frequency of a Vibration

13.6 Audible and Inaudible Sounds

13.7 Noise and Music

13.8 Noise Pollution

NCERT Class 8 Physics Chapter 13 Exercise Solutions: Important Formulas and Points

Sound:

Sound is a form of energy produced by vibrating objects.
It travels in the form of waves.
Sound waves require a medium (solid, liquid, or gas) for propagation.

Properties of Sound:

Sound travels in the form of compressional waves.
The speed of sound depends on the medium it travels through.
Sound waves can be characterized by their frequency (pitch) and amplitude (loudness).

Production of Sound

Sound is produced when an object vibrates.
The vibrating object sets surrounding air molecules into vibration, creating a sound wave.

Formula for calculating the frequency of a sound wave

Frequency = speed of sound/wavelength

Formula for calculating the loudness of a sound:

Loudness = (power of the sound) / (distance from the source of the sound)

Audible and Inaudible Sounds

Sounds with frequencies below 20 Hz are infrasound (inaudible).
Sounds with frequencies above 20,000 Hz are ultrasound (inaudible to humans).

NCERT solutions for class 8 science chapter 13 Sound: Points to remember

Sound requires a medium to travel. This medium can be a gas, liquid or solid. Questions are discussed based on this concept in the NCERT solutions for class 8 science chapter 13 sound.
Hearing is a process in which eardrum senses vibration and send signals to the brain.
Larger the amplitude, the louder will be the sound. Larger the frequency more will be the pitch
Some sounds are pleasant as that of a musical instrument and some are unpleasant as that coming from horns, some home appliances and factories, etc.
The range of audible frequency for humans is 20 to 20000 Hz and more you will get in NCERT.
Noise pollution is caused due to excessive unpleasant sounds. This can cause various health problems. Questions based on this are discussed in CBSE NCERT solutions for class 8 science chapter 13 sound.

Key features of sound Class 8 questions and answers

Comprehensive Coverage: These sound class 8 ncert solutions encompass all the important topics related to sound in the Class 8 curriculum.
Concept Clarity: The answers provide clear and concise explanations to ensure students understand the concepts thoroughly.
Variety of Questions: The class 8 science chapter 13 ncert solutions cover a range of topics, including the properties of sound, how sound travels, and its applications.
Practice Questions: Multiple practice questions of class 8 sound ncert solutions help students reinforce their understanding and problem-solving skills.
Visual Aids: Diagrams and illustrations in science chapter 13 class 8 solution are included where relevant to enhance understanding.
Free Access: These class 8 science ch 13 question answer are freely accessible, making them available to all students for study and revision.

These features make ch 13 science class 8 a valuable resource for students, facilitating their understanding of the subject and preparation for exams.

Also Check NCERT Books and NCERT Syllabus here:

Frequently Asked Questions (FAQs)

1. What is frequency?

Frequency is number of cycles per second. Frequency is measured in Hz. 1Hz=1/1 second

2. What produces sounds in human?

The vibration of vocal cords inside the larynx produce sound

3. What is the relation between pitch and frequency

Pitch is proportional to frequency.

Also Read

NCERT Solutions for Class 8 Science Chapter 11 Force and Pressure

NCERT Solutions for Class 8 Science Chapter 10 Reaching The age of adolescence

NCERT Solutions for Class 8 Science Chapter 9 Reproduction in Animals

NCERT Solutions for Class 8 Science Chapter 7 Conservation of Plants and Animals

NCERT Solutions for Class 8 Science Chapter 3 Synthetic Fibres and Plastics

NCERT Solutions for Class 8 Science Chapter 2 Microorganisms Friend and Foe

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