Two tuning forks A and B initially produce 6 beats per second. Fork A is then filed so that its frequency increases by 4 Hz, while fork B is left unchanged. The new beat frequency becomes 2 beats per second. Which statement must be true about the original frequencies?
Options

Question

Two tuning forks A and B initially produce 6 beats per second. Fork A is then filed so that its frequency increases by 4 Hz, while fork B is left unchanged. The new beat frequency becomes 2 beats per second. Which statement must be true about the original frequencies?

Options

G1 Physics · Accepted Answer

Initially, |f₁−f₂| = 6. After filing fork A, |f₁+4−f₂| = 2. If fork A were initially 6 Hz below B, f₂−f₁ = 6. Then, f₂−(f₁+4) = 2, which agrees with the new beat frequency. If fork A were initially 6 Hz above B, increasing its frequency by 4 Hz would make the difference 10 Hz. Therefore fork A was originally 6 Hz lower than fork B. Correct option: A.