Beats: The tension in each of two strings is adjusted so that both vibrate at exactly 666 Hz. The tension in one of the strings is then increased slightly. As a result, six beats per second are heard when both strings vibrate. What is the new frequency of the string that was tightened?
A) 672 Hz
B) 660 Hz
C) 669 Hz
D) 663 Hz

Question

Quizplus · Accepted Answer

The frequency of the tightened string is 672 Hz because the beat frequency is the absolute difference between the two frequencies, and since 6 beats per second are heard, the new frequency must be either 6 Hz higher or lower than 666 Hz. Since the string is tightened, its frequency increases, making it 666 Hz + 6 Hz = 672 Hz.

Beats: the Tension in Each of Two Strings Is Adjusted