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Chapter Analysis
Intermediate15 pages • EnglishQuick Summary
The chapter on Sound in Class 8 Science explores how sound is produced by vibrating objects and how it requires a medium to travel. It explains the functioning of the human ear, the concepts of amplitude, frequency, loudness, and pitch, and discusses the effects of noise pollution. The chapter includes detailed discussions and activities to help students understand the phenomenon of sound propagation through different media such as solids, liquids, and gases.
Key Topics
- •Sound Production
- •Propagation of Sound
- •Hearing Mechanism
- •Noise and Music
- •Noise Pollution
- •Amplitude and Loudness
- •Frequency and Pitch
- •Audible and Inaudible Sounds
Learning Objectives
- ✓Understand how sound is produced by vibrating objects.
- ✓Explain how sound travels through different media.
- ✓Describe the functioning of the human ear.
- ✓Define the concepts of amplitude, frequency, loudness, and pitch.
- ✓Identify sources and effects of noise pollution.
- ✓Engage in activities demonstrating sound propagation.
Questions in Chapter
A pendulum oscillates 40 times in 4 seconds. Find its time period and frequency.
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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?
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Identify the part which vibrates to produce sound in the following instruments: (a) Dholak (b) Sitar (c) Flute
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What is the difference between noise and music? Can music become noise sometimes?
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List sources of noise pollution in your surroundings.
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Explain in what way noise pollution is harmful to humans.
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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.
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Sketch larynx and explain its function in your own words.
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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?
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Additional Practice Questions
What is the relationship between frequency and pitch of a sound?
easyAnswer: The frequency of a sound wave determines its pitch. Higher frequency results in a higher pitch, while a lower frequency results in a lower pitch.
Describe how sound travels through solids.
mediumAnswer: Sound travels through solids by causing the particles in the solid to vibrate. These vibrations transfer the energy of the sound wave through the solid medium.
How does the human ear process sound?
hardAnswer: The human ear processes sound by capturing sound waves with the outer ear, transmitting them through the ear canal to the eardrum, which vibrates and passes these vibrations to the inner ear, where they are converted into electrical signals sent to the brain.
Why don't we hear sounds from all vibrating objects?
mediumAnswer: We don't hear sounds from all vibrating objects because the human ear can only perceive sounds with frequencies between 20 Hz and 20,000 Hz. Sounds outside this range are inaudible.
Explain the concept of noise pollution and its effects on health.
mediumAnswer: Noise pollution is the presence of excessive or harmful levels of noise in the environment. It can lead to health problems like stress, high blood pressure, sleep disturbances, and hearing loss.
NCERT Exemplar
AvailablePractice with NCERT Exemplar problems and solutions for this chapter. Exemplar problems are designed to help you master the concepts with advanced-level questions.
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