Question

There is a set of four tuning forks, one with the lowest frequency vibrating at 550 Hz. By using any two tuning forks at a time, the following beat frequencies are heard: 1, 2, 3, 5, 7, 8. The possible frequencies of the other three forks are

• A. 552, 553, 560
• B. 557, 558, 560
• C. 552, 553, 558
• D. 551, 553, 558

Answer 1

The correct option is D 551, 553, 558

When two or more sine waves are combined, there are components found that are the sum and difference of the waves.

The differences or the difference is where the beats are found. The differences are found by subtracting one frequency from another.

eg: $551-550=1$

$553-551=2$

$553-550=3$ and so on.

More generally, $F_{beat}=f_1-f_2$