NCERT Solutions for Class 8 Science Chapter 13
Science is beneficial. Science produces powerful and trustworthy knowledge. It may be used to create new technology, treat diseases, and solve various other issues. The research is ever ongoing. Science is constantly improving and increasing our understanding of the cosmos, which raises new issues for future research. However, science can never be “completed.”
NCERT Class 8 Science Chapter 13 is Sound. Students will be briefed on important issues that illustrate the relevance and role of Sound in our daily lives. The back-and-forth movement of an item is known as vibration. To travel, Sound needs a medium. As a result, it can’t travel through space. Therefore, sound is very vital in our lives.
Extramarks NCERT Solutions provide detailed and authentic answers to all the textbook questions. Through those, the students can understand, remember and retain answers to NCERT questions and thus, perform well in exams.
Going through the NCERT Solutions of each Chapter is a secret passage to achieve excellent results in the examination. To help the students, Extramarks has come up with the Class 8 Science Chapter 13 Solution. These solutions are made as per the requirements of students. Class 8 NCERT Solutions of Sound are written comprehensively.
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Key Topics Covered in NCERT Solutions for Class 8 Science Chapter 13
Mentioning below the key concepts covered in NCERT Solutions for Class 8 Science Chapter 13- Sound:
| What is Sound? |
| Sound Waves |
| Types of Sound |
| Sound Properties |
| Characteristics of Sound |
| Sounds by Humans |
| Amplitude, Time Period and Frequency |
| Noise Pollution |
Let us now look at Extramarks’ in-depth information on each subtopic in NCERT Solutions for Class 8 Science Chapter 13- Sound.
What is Sound?
Sound is described as vibrations that can travel through any material, such as air, and are audible when reaching an individual’s or animal’s ear. Musical Sound is described as a sound that is attractive to the ear, whereas Noise is defined as a jarring or unpleasant sound.
Sound is significant because it may take us in directions that vision alone cannot. It may also be significant since it can assist us in determining what we perceive. The Sound may also provide information about a character, location, and time. It facilitates communication between us. Simply hearing footsteps or hearing a voice might help us detect someone’s presence. NCERT Solutions for Class 8 Science Chapter 13 lets students know how important Sound is for a living being.
Sound Waves
NCERT Solutions for Class 8 Science Chapter 13 describes a sound wave as a pattern of disruption created by sound energy travelling away from its source. Longitudinal waves are sound waves where the direction of particle vibration is parallel to the path of energy wave transmission. The atoms vibrate back and forth when they are placed in a beat. A high-pressure and low-pressure zone in the medium occurs from this constant back and forth action. Compressions and rarefactions, respectively, are high-pressure and low-pressure zones.
Transverse Waves
- In Transverse waves, the particle’s direction of motion is perpendicular to that of wave motion.
- This Mechanical wave is a transverse wave, e.g., light, or even a Mexican wave at a stadium.
Longitudinal Waves
- When the medium’s particles migrate parallel to the wave motion’s direction through sequential compression or rarefaction.
- It’s a mechanical wave, too.
- Consider a slinky.
Types of Sound
As per the NCERT Solutions for Class 8 Science Chapter 13, Sound can be divided into two categories:
Inaudible Sound
The frequency of inaudible noises is over 20,000 Hz or below 20 Hz. A sound at this frequency level is inaudible to the typical human ear.
- Infrasonics are low-frequency noises that are inaudible to the human ear.
- Ultrasonics are high-frequency noises that are inaudible to the human ear.
Audible Sound
The audible noises are vibrations at 20 to 20,000 hertz (20 kHz). This frequency level is audible to the human ear.
Sound Properties
To travel, Sound needs a medium. A medium is a substance or material that allows Sound to travel.
Sound cannot travel in a vacuum.
Characteristics of Sound
Extramarks NCERT Solutions for Class 8 Science Chapter 13 discusses the three fundamental characteristics of Sounds in the following:
- Loudness: Loudness is an acoustic feeling that allows people to discern between faint and loud sounds. The Sound generated will be more perceptible if the amplitude of vibrations is greater. This is because the cube of the amplitude of a wave is exactly proportional to its loudness.
- Pitch: Pitch is a sound property that allows people to discriminate between soft and harsh sounds. The vibration frequency is directly proportional to the pitch and shrillness and increases or decreases with it.
- Quality: Quality is a sound quality that allows people to discern between musical sounds produced by different singers or musical instruments, even if their volume and pitch are the same.
Sounds by Humans
How do Humans Produce sounds?
To answer this question, Extramarks NCERT Solutions for Class 8 Science Chapter 13 states:
- The larynx generates the Sound, positioned at the top of the windpipe.
- In the voice box, two vocal cords span across each other and have a slot through which the lungs push air out.
- The voice cords’ muscles control how tight or loose they are.
Human Ear
Extramarks’ NCERT class 8 science chapter 13 explains that the human ear comprises three parts: External Ear, Middle Ear, and Internal Ear.
- Pinna (outer ear) collects Sound from the environment.
- The auditory canal is like a tube through which Sound travels.
- When Sound strikes the eardrum (tympanic membrane), it vibrates.
- Vibrations are sent to the inner ear, and after receiving, they send signals to the brain through the auditory nerve.
Amplitude, Time Period and Frequency
Extramarks’ NCERT Solutions for Class 8 Science Chapter 13 explains the concept of Amplitude, Time Period and Frequency in the following points:
Amplitude
The maximum extent of vibrations produced by any vibrating body from its mean location is amplitude. The amount a radio wave goes back and forth is an example of amplitude.
Time Period
An oscillation is a full to-and-fro movement of the pendulum from its mean position. The Time Period is the time it takes for a vibrating particle to complete one oscillation.
Frequency
Frequency is the number of oscillations per second—Hertz unit of measurement (Hz).
Noise Pollution
Noise pollution is often characterised as repeated exposure to high sound levels that cause harm to people or other living beings. However, according to the World Health Organization, sound levels below 70 decibels do not harm living beings, regardless of how long or constant the exposure is.
Unwanted Sound (Noise) may be harmful to one’s health. Cardiovascular problems, hypertension, excessive stress levels, tinnitus, deafness, sleep difficulties, and various other detrimental and unsettling impacts are all linked to sound pollution. Environmental Noise or noise pollution is the spread of Noise that has multiple effects on human or animal life activities, most of which are damaging to some extent.
Outside Noise is mainly created by machines, transportation, and propagation systems. Poorly designed urban areas can often lead to noise disintegration or pollution; for example, sound pollution in residential neighbourhoods can be caused by industrial and residential buildings being built next to one other. Loud music, transportation (traffic, rail, aircraft, etc.), lawn care maintenance, construction, electrical generators, explosions, and other people are some of the most common noise sources in residential neighbourhoods. Noise can increase the risk of mortality in animals by disrupting predator and prey detection and avoidance, interfering with reproduction and navigation, and contributing to irreversible deafness. The water absorbs a large portion of the Noise that humans make.
Experts have focused on noise pollution in NCERT Solutions for Class 8 Science Chapter 13 straightforwardly, which will help students understand how excessive and undesired sounds the source of noise pollution may be. The noise pollution is caused mainly by human-made voices. Bursting crackers, loudspeakers, and the Sound of automobiles are the most common sources of noise pollution.
NCERT Solutions for Class 8 Science Chapter 13 Exercise and Solutions
Extramarks’ website is full of quality study material. Great resources such as previous year’s question papers, revision notes, extra problems, and more are available for all the classes. Click on the below links to view NCERT Solutions for Class 8 Science Chapter 13:
- Class 8 Science Chapter 13: Very Short Answer Type Questions
- Class 8 Science Chapter 13: Short Answer Type Questions
- Class 8 Science Chapter 13: Long Answer Type Questions
Extramarks NCERT solutions provide detailed and authentic answers to all the textbook questions. Through those, the students can understand, remember and retain answers to NCERT questions and thus, perform well in exams.
Students can easily access NCERT Solutions for Class 8 Science Chapter 13 and other chapters by clicking here. In addition, students can also explore NCERT Solutions for other classes below.
By getting access to NCERT Solutions for Class 8 Chapter 13, students can easily understand all the concepts of Sound.
NCERT Solutions Class 8 Science Chapter-wise List
Key Features of NCERT Solutions for Class 8 Science Chapter 13
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