[1 Mark Question Answer]

Question 11 Mark

The speed of sound is $310 ms^{-1}$. A person fires a gun. An echo is heard after 1.5 s . Calculate the distance of the person from the cliff from which the echo is heard.

Answer

Given, Speed sound, $V=310 ms^{-1} ; t=1.5 s$
$\therefore d=\frac{t \times V}{2}=\frac{1.5 \times 310}{2}=232.5 m$

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Question 21 Mark

(a) What determines pitch of sound?
(b) (i) Name one factor which affects the frequency of sound emitted due to vibrations in an air column.
(ii) Name the unit used for measuring the sound level.

Answer

(a) The frequency of a vibrating body and its effect in the ear determines pitch of sound.
(b) (i) The length of vibrating air column affects its frequency. More the length of vibrating air column lesser is its frequency.
(ii) Decibel $( dB )$ is the unit used for measuring sound level.

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Question 31 Mark

What are reverberation? Give two examples.

Answer

When series of reflected sound from the different reflectors fall on the ears one after another, thereby giving rise to a rolling sound is called reverberation. Reverberation are heard in big halls or the hills in a closed valley.

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Question 41 Mark

State the laws of reflection of sound.

Answer

Laws of reflection of sound :
1. Angle of incidence is equal to angle of reflection.
2. The incident wave, the reflected wave and the normal lie in the same plane at the point of incidence.

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Physics [1 Mark Question Answer]

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