Physics education research, electronic materials, and the musings of Christopher Moore, Ph.D.

A pair of speakers separated by 0.700 m are driven by the same oscillator at
a frequency of 690 Hz. An observer, originally positioned at one of the speakers, begins
to walk along a line perpendicular to the line joining the two speakers. (a) How far must
the observer walk before reaching a relative maximum in intensity? (b) How far will the
observer be from the speaker when the first relative minimum is detected in the intensity