Revision Notes for Class 8 Science Chapter 13 Sound

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Here we are providing revision notes for class 8 science. We have two types of revision notes for class 8 science (i) Short revision notes (ii) Detailed revision notes. In this article, we are covering short revision notes for CBSE class 8 science Chapter 13 Sound.

Sound Class 8 Revision Notes

Sound: Vibrations that travel through the air or another medium and can be heard when they reach a person’s or animal’s ear.
Musical Sound: The sound which produce a pleasing effect on the ear.
Noise: The sounds which produce a jarring or unpleasant effect.

Types of Sound:
(i) Audible Sound: Vibrations whose frequency lies between 20 Hz to 20,000 Hz (20 KHz) are heard by human ear.
(ii) Inaudible Sound: The sounds having frequencies above 20,000 Hz and below 20 Hz cannot be heard by the normal human ear.

• Low frequency sounds which cannot be heard are called infrasonics.
• High frequency sounds which cannot be heard are called ultrasonics.
  In human beings, the vibration of the vocal cords produces sound.
  Sound travels through a medium (gas, liquid or solid). It cannot travel in vacuum.
  The eardrum senses the vibrations of sound. It sends vibrations to the inner ear. From there, the signal goes to the brain. That is how we hear.

Higher the frequency of vibration, the higher is the pitch, and shriller is the sound.
Unpleasant sounds are called noise.

Excessive or unwanted sounds lead to noise pollution. Noise pollution may pose health problems for human beings. Lack of sleep, hypertension (high blood pressure), anxiety and many more health disorders may be caused by noise pollution. A person who is exposed to a loud sound continuously may get temporary or even permanent impairment of hearing.

Attempts should be made to minimise noise pollution. Silencing devices must be installed in air craft engines, transport vehicles, industrial machines and home appliances.
Plantation on the roadside and elsewhere can reduce noise pollution.
Amplitude: The maximum extent of vibration of the vibrating body from its mean position is known as its amplitude.

Time Period: One complete to and fro movement of the pendulum around its mean position is called one oscillation. The time taken by the vibrating particle to complete one oscillation is called time period.

Frequency:

• The number of vibrations made by the vibrating body in one second is known as its frequency.
• The SI unit of frequency is the hertz (Hz).

Characteristics of Sounds:

(i) Loudness: The sensation produced in the ear which enables us to distinguish between a loud and a faint sound. Larger the amplitude of vibration, the louder is the sound produced. It is proportional to square of the amplitude.
(ii) Pitch: The characteristics of sound which distinguishes between a shrill sound and a soft sound. Higher the frequency of vibration, higher is the pitch and shrillness.
(iii) Quality: Characteristic which enables us to distinguish between musical notes emitted by different musical instruments or voices even though they have the same pitch and loudness.

Chapter List

Chapter 1 Crop Production and Management
Chapter 2 Microorganisms: Friend and Foe
Chapter 3 Synthetic 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

Benefits of Using One Page Revision Notes for Class 8 Science

Here are the benefits of using one-page revision notes for CBSE Class 8 Science:

1. Concise Overview: One-page revision notes condense important information from each chapter into a single page, providing a quick and comprehensive overview of the entire syllabus.
2. Time-Saving: These notes save valuable study time as they allow students to quickly review key concepts without going through lengthy textbooks or extensive notes.
3. Effective Recap: One-page notes serve as an efficient tool for last-minute revision before exams, helping students refresh their memory and reinforce their understanding of critical topics.
4. Easy to Carry: Students can easily carry these compact notes anywhere, making them convenient for on-the-go studying, whether at school, home, or during travel.
5. Improved Focus: The condensed format encourages students to concentrate on the most essential points, reducing the risk of distraction from irrelevant information.
6. Enhanced Retention: Summarized information is easier to remember, making it ideal for retaining key concepts and formulas for the exam.
7. Organization: One-page notes often follow a structured format, aiding in the organization of information and making it easier for students to locate specific topics.
8. Quick Reference: During the exam, one-page notes can be used as a quick reference guide to quickly recall important facts and concepts.
9. Boosted Confidence: Having concise revision notes can boost students’ confidence in their exam preparedness, as they can easily review the entire syllabus in a short amount of time.
10. Customization: Students can create their own one-page notes, allowing them to personalize the content to suit their learning style and preferences.
11. Comprehensive Coverage: Despite their brevity, one-page notes should cover all essential topics and concepts, ensuring students don’t miss any important information.

In summary, one-page revision notes for CBSE Class 8 Science offer a convenient and effective way for students to review and consolidate their knowledge, ultimately aiding in better exam performance.