Two loudspeakers, A and B, are driven by the same amplifier and emit sinusoidal waves in phase. The frequency of the waves emitted by each speaker is 172 Hz. You are 8.00 m from speaker A. Take the speed of sound in air to be 344 m/s.

What is the closest you can be to speaker B and be at a point of perfectly destructive interference?

Explanation:

Given that

Frequency =172Hz

Speed of sound =344m/s

Distance from A is 8m.

The wave length λ=v/f

Therefore, λ=344/172

λ=2m

for destructive interference, the path difference must be λ/2, the equation for destructive interference

Δr = (2n + 1) λ / 2

For the first interference n = 0

Δr = λ / 2

∆r=2/2

∆r=1m

the closest you can be to speaker B and be at a point of perfectly destructive interference is 1m

compass can be used day and night, cloudy or sunny