Question

The frequency of beats produced air when two sources of sound are activated , one emitting wavelength $32cm,$ other $32.2cm$ is$($ Take $v_{sound}=350m/s)$

• A. 14
• B. 18
• C. 7
• D. 10

Answer 1

Answer: (C)

7

First of all we will find the frequencies of the two sound sources using

$v_{sound}=f\lambda$ or $f=\frac{v_{sound}}{\lambda }$

therefore frequency corresponding to $32cm$ wavelength,

$f_1=\frac{v_{sound}}{\lambda }=\frac{350}{\left(\frac{32}{100}\right)}=1093.75Hz\approx 1094Hz$

frequency corresponding to $32.2cm$ wavelength,

$f_2=\frac{v_{sound}}{\lambda }=\frac{350}{\left(\frac{32.2}{100}\right)}=1086.95Hz\approx 1087Hz$

thus beat frequency will be,

$f_1-f_2=1094-1087=7Hz$.

Option "C" is correct.