Question

PH1123-01, Spring 19 <12.1: Sound and Its Intensity Problem 12.13 Constants Part A One CD player is said to have a signal-to-noise ratio of 84 dB, whereas for a second CD playor it is 97 dB What is the ratio of intensities of the signal and the background noise for the first device? Express your answer using two signiflcant fnigures Submit Request Answer Part B What is the ratio of intenisites of the signal and the background nolse for the second device? Express your answer using two significant figures Submit Request Answer Provide Feedback

Answer 1

We know that SNR is the ratio of Signal power to the noise power

i.e $SNR = \frac{P_{signal}}{P_{noise}}$

Or in dB, $SNR =10\log ( \frac{P_{signal}}{P_{noise}})$

also, power is directly related to intensity square.

so, the ratio of intensity of signal to the intensity of noise is same as the SNR.

For question 1, $\frac{I_{signal}}{I_{noise}} = 10^{8.4}$

   or,    $\frac{I_{signal}}{I_{noise}} = 251188643.2$    answer

Similarly, for question 2,   $\frac{I_{signal}}{I_{noise}} = 10^{9.7}$

or,   $\frac{I_{signal}}{I_{noise}} = 5011872336$    answer