Answer:
0.35 m
Explanation:
Constructive interference occurs when the difference in the distance between the two speakers is
0, λ, 2λ,...
Here λ = v/f = 343/490 = 0.7m
The first point of interference is the initial point which would mean the distance is the trivial solution of 0 .
A microphone is placed half-way between the speakers and then moved along the line joining the two speakers until the first point of constructive interference is found.
Let x be the distance from the midpoint to the next interference.
This occurs when 1.5 + x -(1.5 - x) = 0.7
so 2x = 0.7 which means x = 0.7/2 = 0.35m