Tuning fork A produces 4 beats per second with a standard 300 Hz fork. Wax is added to fork A, lowering its frequency, and the beat frequency increases to 7 beats per second. What was the original frequency of fork A?
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Question

Tuning fork A produces 4 beats per second with a standard 300 Hz fork. Wax is added to fork A, lowering its frequency, and the beat frequency increases to 7 beats per second. What was the original frequency of fork A?

Options

G1 Physics · Accepted Answer

Initially, |f₁−300| = 4. Thus, f₁ = 296 Hz or f₁ = 304 Hz. Wax lowers the frequency. The beat frequency increases from 4 Hz to 7 Hz. If f₁ were 304 Hz, lowering it would initially move it towards 300 Hz and reduce the beat frequency. Therefore f₁ must be below 300 Hz. Lowering it further increases the difference. Hence, f₁ = 296 Hz. Correct option: A.