ICSE Class 8 Physics Question 2 of 17

Sound — Question 2

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Question

Question 2

Two waves have frequencies 256 Hz and 512 Hz, but same amplitude. Compare their:

(i) loudness, and

(ii) pitch.

Answer

(i) Since amplitude of two waves are same so loudness of both the waves will be same.

amplitude of 1st waveamplitude of 2nd wave=11=1:1\dfrac{\text{amplitude of 1st wave}}{\text{amplitude of 2nd wave}} = \dfrac{\text{1}}{\text{1}} = 1:1

So, loudness of first wave : loudness of second wave = 1:1.

(ii) Frequency determines the pitch of the sound.

frequency of 1st wavefrequency of 2nd wave=256512=12=1:2\dfrac{\text{frequency of 1st wave}}{\text{frequency of 2nd wave}} = \dfrac{\text{256}}{\text{512}} = \dfrac{\text{1}}{\text{2}} = 1:2

So pitch of first wave : pitch of second wave = 1 : 2.