Page 134 - Science Class 08

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i Sound is a sensation produced inside the ears by the vibrating air that enters from outside.
i Sound is produce if there is a such vibrating movement of any object that can make the air
vibrate too.
i The movement of a vibrating body moves through one round of vibration back-and-forth is
called its oscillation.
i The maximum displacement of a vibrating body is called its amplitude.

i Sound needs a medium to travel. It cannot travel in vacuum.
i Sound travels the fastest in solids and faster in liquids than in gases.
i Speed of sound is much slower than that of light. That is why we see lighting flash earlier
than we hear thunder of clouds though they are produced at the same time.

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A. Tick (3) the correct op on.
1. Audibility of a sound depends mainly on its:
(a) loudness (b) pitch

(c) source (d) noise
2. The part of the ear that is first affected by a sound is:
(a) ear-lobe (b) ear-drum
(c) ear-ring (d) none of these

3. Out of the three states of ma er, the one that transmits sound the fastest is:
(a) liquid (b) solid
(c) gaseous (d) none of these

B. Write the correct term for.
1. one complete vibra on back-and-forth : ___________________________
2. the me taken by a body for its one oscilla on : ___________________________
3. what the loudness of a sound depends on : ___________________________

4. the medium in which the sound travels the fastest : ___________________________
5. the medium in which the sound travels the slowest : ___________________________

C. Write the correct name for.
1. the number of oscilla ons of a body per second : ___________________________
2. the feature of sound that depends on amplitude : ___________________________
3. the feature of sound depending on frequency : ___________________________

4. the factor on which audibility of sound depends : ___________________________
D. Fill in the blanks.
1. The sound-carrying air enters the ear and strikes the ________________________ .

134 Science-8