Question

Calculate the frequency of beats produced in air when two sources of sound are activated, one emitting a wavelength of 32 cm and the other of 32.2 cm. The speed of sound in air is 350 m/s.

• A. 2 Hz
• B. 7 Hz
• C. 10 Hz
• D. 20 Hz

Answer 1

The correct option is B

7 Hz

Group-I
${\lambda }_1=32cm$ $=32\times {10}^{-2}m$
v = 350 m/s
so $f_1$=frequency=$\frac{350}{32\times {10}^{-2}}$=1093 Hz
Group-II
${\lambda }_2=32.2cm$ $=32.2\times {10}^{-2}m$
v = 350 m/s
$f_2=\frac{350}{32.2\times {10}^{-2}}=1086Hz$
So beat frequency = 1093 - 1086 = 7 Hz