Question

Beats are produced by two waves given by $ {{y}_{1}}=a\sin 200\pi t $ and $ {{y}_{2}}=a\sin 208\pi t $ . The number of beats heard per second is

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

Answer 1

Answer: (C)

Given, $ {{y}_{1}}=\pi sin\text{ }200\text{ }\pi t $ This equation comparing with $ y=a\sin 2\pi {{x}_{1}}t $ Then, $ {{n}_{1}}=100 $ and $ {{y}_{1}}=a\sin 208\pi t $ This equation comparing with $ y=a\sin 2\pi {{n}_{2}}t $ $ {{n}_{2}}=104 $ Hence, the number of beats $ ={{n}_{2}}-{{n}_{1}} $ $ =104-100=4 $