Beats are produced by two waves given by `y_(1)= a sin 2000 pi t` and `y_(2) =a sin 2008 pi t `. The number of beats heard per second is

Options

A. zero
B. one
C. four
D. eight

Answer

C

Explanation

Number of beats per second `=n_(1)~n_(2)`
`omega_(1)=2000pi=2pin_(1)`
`implies n_(1)=1000`
and ` omega_(2)=2008 pi=2pin_(2)`
`implies n_(2)=1004`
Number of beats heard per second `=1004-1000=4`