# Question on destructive and constructive interference

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1. Nov 17, 2016

### WWCY

1. The problem statement, all variables and given/known data
Two speakers A and B are 3.50m apart and each one is emitting a frequency of 444Hz. However because of signal delays, speaker A is 1/4 of a period ahead of B. Find all points relative to the centerline between A and B where there is constructive interference. Include angles on both sides of centerline, speed of sound is 340m/s

2. Relevant equations
dsinθ = (m+?)λ

d = 3.5m
λ = v/f
3. The attempt at a solution

I know there is a need to compensate for the initial 1/4 phase difference as the usual equation assumes both sources are in phase. I just don't know how to do it.

2. Nov 17, 2016

### Staff: Mentor

What is the relation between position and phase?

3. Nov 17, 2016

### WWCY

Is it that any position where 2 waves are half a wavelength out of phase cancel while 2 that are in phase constructively interfere?

4. Nov 17, 2016

### Staff: Mentor

I mean for a single wave.

5. Nov 18, 2016

### WWCY

I apologize but I'm not quite sure of what you're getting at, could you elaborate?

6. Nov 18, 2016

### Staff: Mentor

You said you don't know how to compensate for the phase difference. I'm trying to get you to see the relation between the phase difference and position.

7. Nov 18, 2016

### WWCY

I still can't quite get what you mean by position, apologies.