Question

Two waves of wavelength $1.00 \, m$ and $1.01 \, m$ produces $10 \, $ beats in $3 \, s$ . What is the velocity of the wave?

• A. $150 \, m \, s^{- 1}$
• B. $115.2 \, m \, s^{- 1}$
• C. $336.6 \, m \, s^{- 1}$
• D. $200 \, m \, s^{- 1}$

Answer 1

Answer: (C)

$v_{1}=\frac{v}{\lambda _{1}}=\frac{v}{1.00} \, and \, v_{2}=\frac{v}{\lambda _{2}}=\frac{v}{1.01}$
$\therefore \Delta v=v_{1}-v_{2}=v\left[\frac{1}{1.00} - \frac{0}{1.01}\right]=10$
$or \, \, v=\frac{10 \times 1 \times 1.01}{0.01}=1010 \, for \, 3s$
$\therefore v=336.6 \, m \, s^{- 1}$