The ratio of intensities between two coherent sound sources is `4:1` the difference of loudness in decibels between maximum and minimum intensities, when they interfere in space, is

Options

A. 10 log 2
B. 20 log 3
C. 10 log 3
D. 20 log 2

Answer

B

Explanation

`(I_1)/(I_2) = 4/1 = ((a_1)/(a_2))^2 therefore (a_1)/(a_2) = 2/1 So (a_1 + a_2)/(a_1 - a_2)`
`= 3/1 "So" (I_("max"))/(I_("min")) = 9/1 therefore L = 10 "log" (I_("max"))/(I_("min")) = 10 "log " 9`
`= 20 "log" 3`