Question

Traffic noise on Beethoven Boulevard has an intensity level of 80 dB; the traffic noise on Mozart Alley is only 60 dB. Part A Compared to the sound intensity on Beethoven Boulevard, the sound intensity on Mozart Alley is Compared to the sound intensity on Beethoven Boulevard, the sound intensity on Mozart Alley is a. 25% lower.b. 100 times lower. c. 20 W/m2 lower. d. 20 times lower.

Answer 1

Answer:

option (b)

Explanation:

Io = 10^-12 w/m^2

In Case I:

dB = 80 dB

The formula for the intensity of sound

$dB=10log\left ( \frac{I}{I_{0}} \right )$

$80=10log\left ( \frac{I_{1}}{I_{0}} \right )$

$I_{1} = 10^{8}\times I_{0}$

$I_{1} = 10^{8}\times 10^{-12}=10^{-4}W/m^{2}$   ... (1)

In Case II:

dB = 60 dB

The formula for the intensity of sound

$dB=10log\left ( \frac{I_{2}}{I_{0}} \right )$

$60=10log\left ( \frac{I_{2}}{I_{0}} \right )$

$I_{2} = 10^{6}\times I_{0}$

$I_{2} = 10^{6}\times 10^{-12}=10^{-6}W/m^{2}$   ... (2)

So, by equation 2 and 1 we get

$I_{2}=\frac{I_{1}}{100}$

Thus, the intensity of sound is 100 times lower.