Question

When two tuning forks A and B are sounded together, 4 beats per second are heard. The frequency of the fork B is 384 Hz. When one of the prongs of the fork A is filed and sounded with B, the beat frequency increases, then the frequency of the fork A is

• A. 379 Hz
• B. 380 Hz
• C. 389 Hz
• D. 388 Hz

Answer 1

The correct option is D

388 Hz

We know,

$Beat=|f_A–f_B|$

As number of beats is 4. So the frequency of fork A can be 380 Hz or 388 Hz. When fork A is filed its frequency increases and the number of beats also increases.

Therefore, the frequency of fork A will be 388.