Question

Two tuning forks produce frequencies of 256 Hz and 260 Hz. When sounded together, how many beats are heard per second? If the intensity of both sources is equal, what type of interference occurs at the beat minima?

• A. 2 beats/s, Constructive interference
• B. 4 beats/s, Destructive interference
• C. 4 beats/s, Constructive interference
• D. 2 beats/s, Destructive interference

Hint:

The number of beats per second is the absolute difference between the frequencies of the two sources. Destructive interference occurs when the waves are out of phase.

Answer 1

The Correct Option is B

The number of beats per second is given by the difference in frequencies of the two tuning forks: \[ \text{Beats per second} = |f_1 - f_2| \] where \(f_1 = 260 \, \text{Hz}\) and \(f_2 = 256 \, \text{Hz}\). \[ \text{Beats per second} = |260 - 256| = 4 \, \text{beats/s} \] Now, when the frequencies of the sources are close but not exactly equal, destructive interference occurs at the beat minima, which happens when the sound waves are out of phase. Thus, the number of beats heard is 4 beats/s, and destructive interference occurs at the beat minima.
Final answer
Answer: \(\boxed{4 \, \text{beats/s, Destructive interference}}\)