Physics
posted by Phil .
This question has me very lost.
Two loudspeakers emit sound waves along the xaxis. The sound has maximum intensity when the speakers are 11 cm apart. The sound intensity decreases as the distance between the speakers is increased, reaching zero at a separation of 50 cm. What is the wavelength of the sound?
Also
If the distance between the speakers continues to increase, at what separation will the sound intensity again be a maximum?
I've tried like 5 different ways, none seem to work.
Can someone please how to approach it the correct way.
Thanks in Advance.

The difference between 50 cm and 11 cm must be one half wavelength.
I would expect a max at 50+39cm. 
1/2 wavelength=zero intensitymax intensity
so your wavelenth is going to be 2(5011)=78 cm
For the second half of the question, you already know a max is achieved at 11 cm so to find the answer you just add 11cm to your wavelength
78+11= 89 cm