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:

(1) 5.5 mm, 60 KHz

(2) 330 m, 60 KHz

(3) 5.5 mm, 20 KHz

(4) 5.5 mm, 80 KHz

(1) Frequency of waves remains same, i.e. 60 Hz

and wavelength $\text{​​}\lambda =\frac{v}{n}=\frac{330}{60×{10}^{3}}$= 5.5 mm.

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