When beats are produced by two progressive waves of nearly the same frequency, which one of the following if correct?

Options

A. The particle vibrates simple harmonically , with the frequency equal to the difference in the component frequencies
B. The amplitude of vibration at any point changes simple harmonically with a frequency equal to the difference in the frequencies of the two waves
C. The frequency of beats depends upon the position , where the observer is
D. The frequency of beats changes at the time progresses

Answer

B

Explanation

As ` y = A_(b) sin ( 2 pi n_(av) t)`
where `A_(b) = 2 A cos ( 2 pi n_(A) t)` ltwhere `n_(A) = (n_(1) - n_(2))/(2)`