A physics instructor demonstrates two separate wave phenomena in a laboratory:…
PHYSICS · Multi-part · AP · Physics 2: Algebra-based · Waves Sound and Physical Optics · Waves Sound and Physical Optics
Problem
A physics instructor demonstrates two separate wave phenomena in a laboratory:
Experiment 1: A narrow beam from a green laser pointer passes through a pair of adjustable polarizing sheets. The transmitted intensity is measured with a photodiode.
Experiment 2: A loudspeaker generates a 1.0kHz tone in a long, straight tube of air. Halfway down the tube, the instructor inserts a polarizing grill that consists of parallel rigid plates separated by 2.0cm. A microphone records the sound intensity beyond the grill.
In both experiments, the orientation of the second polarizer or grill can be rotated through 90∘ relative to the first.
(1) Describe qualitatively how the transmitted intensity of the laser beam is expected to vary as the relative angle between the two polarizing sheets is increased from 0∘ to 90∘.
(2) Predict what will happen to the recorded sound intensity as the grill is rotated through the same range of angles, and justify your prediction based on the nature of the sound wave in the tube.
(3) Explain why the contrasting results from Experiments 1 and 2 provide evidence about the fundamental difference between the two wave types involved.