Question

Three sources of equal intensities with frequencies $400,401$ and $402\, vib/s$ are sounded together. The number of beat/s is

• A. zero
• B. 1
• C. 2
• D. 3

Answer 1

Answer: (C)

2

Answer 2

Beats are the periodic and repeating fluctuations heard in the intensity of sound, when two sound waves of very similar frequencies interfere with one another.
Beats = difference in frequencies.
Maximum-number of beats $=402-400=2$