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# Solved Example Problems for Intensity and Loudness of sound

Physics : Waves - Solved Example Problems for Intensity and Loudness of sound

### EXAMPLE 11.23

A baby cries on seeing a dog and the cry is detected at a distance of 3.0 m such that the intensity of sound at this distance is 10-2 W m-2. Calculate the intensity of the baby’s cry at a distance 6.0 m.

### Solution

I1 is the intensity of sound detected at a distance 3.0 m and it is given as 10-2 W m-2. Let I2 be the intensity of sound detected at a distance 6.0 m. Then,

r1 = 3.0 m,

r2 = 6.0 m the power output does not depend on the observer and depends on the baby. Therefore, I2 = 0.25 × 10-2 W m-2

### EXAMPLE 11.24

The sound level from a musical instrument playing is 50 dB. If three identical musical instruments are played together then compute the total intensity. The intensity of the sound from each instrument is 10-12 Wm-2

### Solution I1 = 10-7 Wm-2

Since three musical instruments are played, therefore, Itotal = 3I1 = 3 × 10-7 Wm-2.

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11th Physics : UNIT 11 : Waves : Solved Example Problems for Intensity and Loudness of sound | Physics