Question
Two coherent sources of sound, S1 and S2,
produce sound waves of the same wavelength,
$\lambda $ = 1 m, in phase. S1 and S2 are placed 1.5 m
apart (see fig). A listener, located at L, directly
in front of S2 finds that the intensity is at a
minimum
when he is 2 m away from S2. The
listener moves away from S1, keeping his
distance from S2 fixed. The adjacent maximum
of intensity is observed when the listener is at
a distance d from S1. Then, d is :