In this figure which points represent the points of constructive interference? (a) A, B, F
(b) A, B, C, D, E, F
(c) A, C, D, E
(d) A, B, D

Video Transcript

This is College Physics Answers with Shaun Dychko. We have a pure tone being emitted by two different speakers and we are asked to figure out which points represent the constructive interference between these two sounds? So the dotted lines represent positions where we have rarefaction or low pressure in our sound wave and then the solid blue line represents where we have high pressure or compression and we can see that the compression from one sound wave meets compression from another sound wave at points A and at point C we have a solid blue crossing a solid blue, point D same story and point E so A, C, D and E are all points of constructive interference. So the answer is (c) based on that but I would argue that point B could also be considered constructive interference because we have a point of rarefaction meeting another point of rarefaction, which will be extra... it will be louder there as a result. So... but anyway they don't have an A, C, D, E, B option so our best choice is answer (c).