Question

An underwater sonar source operating at a frequency of $60kHz$ directs its beamtowards the surface. If the velocity of sound in air is $330m/s$, the wavelength and frequency of waves in air are:

• A. $5.5mm,60kHz$
• B. $330m,60kHz$
• C. $5.5mm,20kHz$
• D. $5.5mm,80kHz$

Answer 1

The correct option is A $5.5mm,60kHz$

Given,

Frequency, $f=60kHz=6\times {10}^{4}Hz$

Velocity of sound in air, $v=330m/s$

Wavelength, $\lambda$

We know,

$\lambda =\frac{v}{f}$

$\lambda =\frac{330}{60\times {10}^3}$

$\lambda =5.5\times {10}^{-3}m$

$\lambda =5.5mm$

The frequency is a characteristic of the source. It does not change on the medium.

$f=60Hz$