Question

Two waves of wavelengths 99 cm and 100 cm both travelling with velocity 396 m/s are made of interfere. The number of beats produced by them per second are

• A. $1$
• B. $2$
• C. $4$
• D. $8$

Answer 1

The correct option is C $4$

$\begin{array}{c}VelocityofwaveV=n\lambda \\ Wheren=frequencyofwave\\ \Rightarrow n=\frac{v}{\lambda }\\ n_2=\frac{v_2}{{\lambda }_2}=\frac{396}{100\times {10}^{-2}}=396Hz\\ no.ofbeats=n_1-n_2=4\end{array}$