Tuning fork A has frequency 600 Hz. Tuning fork B produces 7 beats per second with A. Wax is added to B and lowers its frequency by exactly 10 Hz. The new beat frequency is 3 beats per second. If the original frequency of B is N Hz, find N.
Physics · Wave Motion · Beats, Loudness, Pitch and Characteristics of Sound
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Question

Tuning fork A has frequency 600 Hz. Tuning fork B produces 7 beats per second with A. Wax is added to B and lowers its frequency by exactly 10 Hz. The new beat frequency is 3 beats per second. If the original frequency of B is N Hz, find N.

Physics · Wave Motion · Beats, Loudness, Pitch and Characteristics of Sound

G1 Physics · Accepted Answer

Initially, |f₂−600| = 7. So, f₂ = 593 Hz or 607 Hz. After waxing, f₂(new) = f₂−10. If f₂ = 607 Hz, then f₂(new) = 597 Hz, and the new beat frequency is |597−600| = 3 Hz. If f₂ = 593 Hz, then the new frequency is 583 Hz and the beat frequency would be 17 Hz. Therefore, N = 607.