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# Lakhmir Singh Science Class 8 Solutions Sound (Chapter 13)

Lakhmir Singh and Manjit Kaur Solutions for Class 8 Science Chapter 13 – Sound are very important to study for your exams. The chapter describes how the sound is produced, how we hear the sound, how it travels from one place to another, why some sounds are larger than others. All of these concepts have been educated with the help of descriptive diagrams and out of the box explanations.

Other main topics of chapter 13 Sound of Lakhmir Singh Solution for Class 8 Science includes sound is produced by a vibrating body, sound produced by humans, sound needs a medium of propagation, we hear sound through our ears, amplitude, time period, and frequency of a vibration, audible and inaudible sounds, noise and music, noise pollution, its causes, effects and control measures.

Lakhmir Singh Solutions Class 8 Science Chapter 13 Sound has a total of 5 exercises with around 123 questions. The solutions are developed by the subject matter experts at Instasolv who hold great experience in the domain. Following the solutions provided by Instasolv will not only develop a grip on these topics but also master the concepts that will help you to perform better in your exams.

## Important Topics for Lakhmir Singh Solutions for Class 8 Science Chapter 13  Sound

Introduction to Sound

Sound plays a significant role in our life. It is through sound we hear someone and understands what the person wants to say. Vibrating objects also produces sound. However, sound needs a medium to travel. Hence, it cannot travel in a vacuum.

Introduction to waves

The sound is generated by vibrating objects. They travel from one place to another in the form of waves. Therefore, named as sound waves.

Wave and Particle Motion of Waves

Mechanical waves are waves that travel through a physical medium. Generally, it is categorized into two types depending on the direction of motion of the particle and the wave propagation:

• Transverse Waves
• Longitudinal Waves

What are Sound Waves?

Sound needs a medium to transmit. The material through which sound propagates is known as a medium. However, the sound cannot travel in a vacuum. The moon does not have an atmosphere, hence, you can’t hear on the moon.

How do Humans Produce Sound?

The sound generated in the voice box called larynx situated at the upper end of the windpipe. 2 vocal cords get strained across in the voice box. It has a slit, through which air is pushed out by the lungs. Thus, muscles close to vocal cords make it tight or loose.

Human Ear

• Outer ear = pinna: collects sound from the atmosphere.
• The sound goes through a tube known as an auditory canal.
• The eardrum then vibrates when the sound occurs.
• Vibrations are sent to the inner ear, from there it goes to the brain as signals via the auditory nerve.

Amplitude, Frequency and Time Period of Vibrations

• The magnitude of disruption in the medium on either side of the mean value is known as Amplitude (A). Higher the amplitude, louder the sound.
• The number of oscillations per second is termed as frequency. It is expressed in Hertz (Hz).
• Time is taken for one complete oscillation to travel across a point. T = 1/f. (Seconds)

Noise and Music

Sounds with the same pitch and loudness can be notable based on the quality. Music is enjoyable to the ears while noise is not. Here, unpleasant sounds are called noise.

Noise Pollution and Measures to Control It

The presence of extreme unwanted noise in our atmosphere is called noise pollution. It can cause hearing impairment, sleeplessness, and also hypertension. Noise pollution must be reduced by decreasing noisy operations and beeping in residential areas. Planting trees along roads also cut down the noise.

### Exercise-Wise Discussion of Lakhmir Singh Solutions for Class 8 Science Chapter 13 Sound

Chapter 13 Sound has a total of 5 exercises with around 123 questions. You will find the exercise-wise solutions in a step-by-step manner below, making it easy for you to learn the topics in no time.

Exercise 1 – Very Short Answer Type Questions

The first exercise of the chapter has around 50 questions which are very short answer type questions based on how the sound is produced, how do we hear the sound, how does it travel from one place to another, and why are some sounds larger than others.

Exercise 2 –Short Answer Type Questions

This exercise of Chapter 13 Sound has around 37 questions which are short answer type questions. Practising these questions will help you clear your concepts.

Exercise 3 –Long Answer Type Questions

Lakhmir Singh Class 8 Science Solutions Chapter 13 Exercise 13.3 consists of a total of 11 questions which are long answer type questions. Practising these questions will help you in preparing for your CBSE exams well.

Exercise 4 –Multiple Choice Questions (MCQs)

Exercise 4 of Lakhmir Singh Solutions for Chapter 13 consists of 20 questions that are multiple-choice questions.

Exercise 5 – Questions Based on High Order Thinking

This is the last exercise of the chapter and has around 5 questions which are based on high order thinking.

If you face issues in solving the questions, you can refer to Lakhmir Singh Solutions for ‘Sound’ prepared by the experts at Instasolv.

## Benefits of Lakhmir Singh and Manjit Kaur Solutions for Class 8 Science Chapter 13 Sound

The useful benefits of the Lakhmir Singh Class 8 Science Solutions Chapter 13 Sound are provided below:

• Our Lakhmir Singh solutions cover the complete chapter and the main topics of the exam.
• Solutions to the questions provide an edge to you over the others because the solutions are accurate and to the point.
• All the concepts and solutions of the questions in our Lakhmir Singh Solutions are error-free.
• The major part is that the solutions developed by us are free of cost for you.
• Scoring marks will become easy for you with the help of the Lakhmir Singh and Manjit Kaur Solutions for Class 8 Science.
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