Physics · Principle of superposition of waves, reflection of waves, standing waves in strings and organ pipes, fundamental mode and harmonics, beats
When two tuning forks and are sounded together, 4 beats per second are heard. Th
When two tuning forks \( A \) and \( B \) are sounded together, 4 beats per second are heard. The frequency of the fork \( B \) is \( 384 H z . \) When one of the prongs of the fork \( A \) is filed and sounded with \( B \), then beat frequency increases, then frequency of the fork \( \boldsymbol{A} \) is
- A. \( 380 H z \)
- B. 388 Нг
- C. 379 Н \( z \)
- D. \( 389 ~ H z \)
Step-by-step solution
Initially, beat frequency = |f_A - 384| = 4 Hz, so f_A is either 380 Hz or 388 Hz. Filing a prong decreases frequency. If f_A were 388 Hz, filing would bring it closer to 384 Hz, decreasing beat frequency. But beat frequency increases, so f_A must be 380 Hz, which becomes even lower after filing, increasing the difference and beat frequency.