Q58PP - University Physics with Modern Physics

Question

The professor returns the apparatus to the original setting. She then adjusts the speakers again. All of the students who had heard nothing originally now hear a loud tone, while you and the others who had originally heard the loud tone hear nothing. What did the professor do? (a) She turned off the oscillator. (b) She turned down the volume of the speakers. (c) She changed the phase relationship of the speakers. (d) She disconnected one speaker.

Step-by-Step Solution

Answer

The correct option is D

Step 1: Important Concepts

The properties of sound and reflection of sound.

Constructive and destructive interference.

Step 2: Application

Now you hear nothing while other students, who were hearing nothing in the beginning, are hearing the loud tune. This means that the position in which constructive interference occurs is replaced by destructive interference. This happens only (since the system is constant) when the phase of the two speakers is changed by half wavelength. So, the professor changed the phase relationship of the speakers.