Q. An underwater sonar source operating at a frequency of $60\ kHz$ directs its beam towards the surface. If the velocity of sound in air is $330\ m/s,$ the wavelength and frequency of waves in air are:
A) $5.5\ mm,\ 60\ kHz$
B) $330\ m,\ 60\ kHz$
C) $5.5\ mm,\ 20\ kHz$
D) $5.5\ mm,\ 80\ kHz$
Explanation
(a) Frequency of waves remains same, $i.e.\ 60\ kHz$
and wavelength $\lambda = \frac{v}{n} = \frac{330}{60 \times 10^{3}} = 5.5\ mm$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.