Question

A source of sound of frequency 600 Hz is placed inside water.The speed of sound in water is 1500m/s,and in air,it is 300m/s.The frequency of sound recorded by an observer who is standing in air is: a)200 Hz. b)120 Hz. c)3000 Hz. d)600 Hz.

Answer 1

The frequency made under water will be the same when heard in air outside the water, because frequency not depends on the propagation medium, but it depends on the vibration source (ν=600 Hz).
Answer: d)600 Hz.