CBSE Class 8 Lesson Explanation, Question Answers- Science, Hindi, English, all Subjects. Question 3. The base loudness level is defined as that loudness of sound that the human ear can just perceive. The principle of reflection of sound is used in SONAR. create sound pollution. vibrating object moves backward, it forms a region of low pressure called rarefaction (R). Thus, we can conclude that vibrating body produces sound. No. Justify with an experiment. If the eardrum is absent we would not be able to hear. What is the time period of the vibration? The pressure variation in a sound wave causes vibrations in the eardrum. Answer: On striking the metal dish we hear sound and on touching it we feel the dish vibrating. When a tuning fork is hit on a rubber pad, a faint sound is heard but no vibrations are seen. Question: Why are we not able to hear the screams of a bat? (b) its frequency is below 20 Hz. Top. Question 20. If not why ? Take a bucket or a bathtub. Question 4. But as we start removing air by means of vacuum pump, the sound of ringing bell goes on becoming fainter or lighter. Its unit is m/sec. It includes three interlocked bones: The sound which is pleasing to the ear called _______sound. About NCERT solutions Class 8 Science Chapter 13 Sound. Students can revise the Class 8 Science chapter Sound solutions before sitting in the exams. It is, Outer part: It consist of ear pinna, auditory canal, and ear drum. If the amplitude of vibration is large, the sound is feeble. 3. However, the sound produced by the flapping wings of a crow has a very low frequency of less than 20 Hz, so it is not audible to humans. Answer: Question 22. Students who are in Class 8 or preparing for any exam which is based on Class 8 Science can refer NCERT Science Book for their preparation. We cannot hear the sound of the exploding meteors in the sky, though we can see them. Why should we never put a sharp, pointed or hard, thing into our ear? 7. It cannot travel through vacuum. SCIENCE OF SOUND 'SCIENCE OF SOUND' is a 14 letter phrase starting with S and ending with D Crossword clues for 'SCIENCE OF SOUND' Clue Answer; Science of sound (9) ACOUSTICS: Sound properties (9) Synonyms, crossword answers and other related words for SCIENCE OF SOUND … Answer: Bat produces ultrasonic sound during screaming and that is the frequency of a sound is more than 20,000Hz,  it cannot be heard by us. Physically, the ear consists of three parts: the outer ear, the middle ear, and the inner ear. A child having hearing impairment can not speak because if he is able to hear, he will leam to speak. Answer: Strike the tablespoon gently at the brim of the tumbler. In which case is the amplitude larger? Inner part: This contains the sensory organs for balance and motion, with the help of semicircular canals. Now ask your friend to speak”Hurrey, Hurrey”from the open end (Fig. This is partly because men are normally larger than women (sexual dimorphism), which means their vocal folds are larger. Calculate the speed of sound. Explain the sound wave in terms of amplitude and wavelength. This is the reason why the voices of men, women and children are different. Light can travel through vaccum. a) Higher than 20,000 Hz. Answer: Solid Question 3. Vibrations in the air are called travelling longitudinal waves, which we can hear. The number of oscillations per second of a vibrating object is called its time period. What is the reason for the difference between the two? These ncert book chapter wise questions and answers are very helpful for CBSE exam. Why do the grain jump up and down? d) Lower than 10,000 Hz 10 Voice of man is heavy compared to a woman because These instruments struck themselves as they include vibrating membranes as used in drums of various kinds. Define vibration. ∴ Time period = 1/500 second. What is their function ? Loudness is proportional to the square of the amplitude. The amplitude (volume) and frequency (pitch) of the sound wave depends on what the source is and the amount of energy supplied outwards. The pitch of sound depends on which of the following? Answer: 4. On receiving vibrations, the ear drum starts vibrating. NCERT Solutions for Class 8. Explain how the sound travels. Bats produce ultrasonic sound during screaming. Answer: Students can revise the Class 8 Science chapter Sound solutions before sitting in the exams. But, the people standing around us cannot hear the same sound or we can say that it is limping not audible to them. 13.4). (c) occur together but the thunder is observed a little after the lightning. For example: These instruments struck themselves as they include vibrating membranes as used in drums of various kinds. And having tiny hair cells inside circular wave are produced and high pressure... 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