Question

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

• A. two
• B. One
• C. Four
• D. Eight

Answer 1

The correct option is C Four

Number of beats per second $=n_1\sim n_2$
${\omega }_1=2000\pi =2\pi n_1$
$\Rightarrow n_1=1000$ and ${\omega }_2=2008\pi =2\pi n_2$
$\Rightarrow n_2=1004$
Number of beats heard per second $=1004-1000=4$.