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on of th vocal cords produces sound. G asshopp, the rough edges of their wings against the upper part o, , ‘through vacuum. It propagates through Bases, liquids org, ' medium. The speed of sound in air is 330 ms”. OF $9, , drum senses tions of sound. It sends the signals to the brain, a f vibration, the higher js the, , s is called hearing. Higher the frequency 0, , and shriller is the sound. , . j, . S.The human ear can hear sounds only in a certain range of frequencies, 20 Hz ~ 290995,, , Sounds that are pleasing to the ear are called music. Unpleasant sounds are cally, noise. Larger the amplitude of vibrations, the louder is the sound., , “7. Excessive or unwanted sounds lead to noise pollution. Noise pollution may Pose eal, : problems for human beings. Plantation on the roadside and elsewhere can reduce noise politi, 8 Tuning fork produces waves on the surface of water., 9. The frequency of a sound is a number of vibrations produced per second. The maximuy, displacement of the vibrating body from its mean position is called its amplitude., 10. The to-and-fro motion of vibrating particle about its mean position is called, Frequency is the number of oscillations per second. It is expressed in hertz, Frequency determines the shrillness or pitch of a sound, ‘The loudness of sound depends on its amplitude. When the amplitude of vibrati, ‘Tange, sound produced is loud. When amplitude is small the sound produced is, TX) The vocal cords in men are about 20 mm long, in women these are about 151, While in children these are very short. a, , 4, / , te:, , Scanned with CamScanner

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© noise, , , , RS, noise, , , , , , , , , ah, eae the suitable word event json Tyee rnin, solids v ———— %, c ‘ac i :, uum: ultrasonic vibrations noise. h, , , , , , , , , , mals like dogs, dolphins, b, = ats can hear the DiGaceuce ib colon., +4, , ind cannot travel through VAC, range of Rs cana i, e . ., Byund travels faster in CS is above 20,000 Hz., The pollution produced by Donycoice © fies:, i is called noise pollution., tch the items in column A with those in column B : ., i Column A :, : s ‘a Column B iz, J 4, The to and fro or back and forth motion of an object (a) Frequency =, \* The number of vibrations produced by a vibrating |(b) 330 ms"!, | particle or a body in one second _ g, 3, Necessary for the propagation of sound -A (c) dB, 4 Speed of sound in the air _ bb (d) Material medium, 5, Maximum displacement of vibrating body from its |(e) Amplitude, , , , , , , , , , , , ‘} mean position -~— ©, | 6, The unit of loudness of sound - C, , , , (f) Vibration, , , , , , D. Write ‘True’ or ‘False’ in front of the statements given below :, ‘1, Sound travels faster in solids than fluids., , ae, 2. The sound can travel through vacuum. &, hie =, pep ss, 4, :, , , , , , , , , , , , , , 3, Sound energy travels in the form of waves., , Ultrasonic vibrations have a frequency less t, Most vibrating objects produce sound of one, , han 20,000 Hz., frequency only., , , , , ‘ort answer type questions +, , the sound which has pleasant sensation on the ears., , Scanned with CamScanner