A loudspeaker L is placed between a microphone M and a screen S reflecting sound waves. The loudspeaker emits sound of fixed wavelength $\lambda$ in all directions. When the screen is moving slowly, to the right along the $x$ direction (slowly compared to the speed of sound), the microphone records minima and maxima of the sound intensity. What is the distance between 2 screens giving 2 successive maxima? Would the microphone record minima and maxima if (a) the loudspeaker or (b) the microphone is moving along $x$ direction instead of the screen?
I have no idea how to do this. I'm sure you'd have to express the distance in terms of $\lambda$, but that's about it. One of the problems with this question is what they mean by minima/maxima of sound intensity. So I used to think that a greater sound intensity meant a greater amplitude, but that can't be the case here I believe, because I don't see how this experiment could affect the amplitude of the sound.