13. Sound Class 8 Science [LATEST] Solutions Chapter Review in English - CBSE Study
NCERT Solutions for Class 8 Science are carefully prepared according to the latest CBSE syllabus and NCERT textbooks to help students understand every concept clearly. These solutions cover all important 13. Sound with detailed explanations and step-by-step answers for better exam preparation. Each Chapter Review is explained in simple language so that students can easily grasp the fundamentals and improve their academic performance. The study material is designed to support daily homework, revision practice, and final exam preparation for Class 8 students. With accurate answers, concept clarity, and structured content, these NCERT solutions help learners build confidence and score higher marks in their examinations. Whether you are revising a specific topic or preparing an entire chapter, this resource provides reliable and syllabus-based guidance for complete success in Science.
Class 8 English Medium Science All Chapters:
13. Sound
1. Chapter Review
Chapter Review:
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When an object vibrates, it produces sound.
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When any sound reflects by striking on any medium, that sound heard us again and again. This is called eco sound.
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The audible range of human ears is 20 Hz to 20,000 Hz.
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The S.I unit of frequency is Hz (Hertz).
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The S.I unit of wave length is meter.
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The to and fro or back and forth motion of an object is termed as vibration.
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In humans, the sound is produced by the voice box or the larynx.
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The vocal cords in men are about 20mm long. In women these are about 5mm shorter.
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When air has been removed completely from a vessel, it is said that there is vacuum in the vessel.
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When sound enters in it, it travels down a canal at the end of
which a thin membrane is stretched tightly. It is called the eardrum. -
The to and fro motion of an object is known as vibration. This motion is also called oscillatory motion.
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The number of oscillations per second is called the frequency of oscillation.
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The loudness of sound depends on its amplitude. When the amplitude of vibration is large, the sound produced is loud. When the amplitude is small, the sound produced is feeble.
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The loudness is expressed in a unit called decibel (dB).
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Unpleasant sounds are called noise.
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Some animals can hear sounds of frequencies higher than 20,000 Hz.
Dogs have this ability. -
Sound travels through a medium (gas, liquid or solid). It cannot travel in vacuum.
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