A source emits sound of frequency 600 Hz inside water. The frequency heard in air (velocity of sound in water is 1500 m/s and velocity of sound in air is 300 m/s) will be:

The correct option is 600 Hz.

Step-by-Step Explanation:

When a wave (such as a sound wave) propagates from one medium to another, the properties of the wave behave in the following manner:
1. Frequency: The frequency of a wave is determined solely by the source that produces it. It does not depend on the medium through which the wave travels. Therefore, when a wave transitions from one medium to another (e.g., from water to air), its frequency remains constant.
2. Velocity and Wavelength: The speed of the wave depends on the physical properties of the medium. As the wave transitions from water to air, its speed changes. To maintain a constant frequency, the wavelength also changes in accordance with the wave equation:

$$v=f\lambda$$

where $v$ is the velocity of sound, $f$ is the frequency, and $\lambda$ is the wavelength.

Since the source in water emits sound at a frequency of 600 Hz, the frequency of the sound waves remains exactly the same when they cross the boundary and enter the air. The difference in the speed of sound in water (1500 m/s) and air (300 m/s) only causes the wavelength of the sound to change, while the frequency remains completely unaffected.

Thus, the frequency heard in air is:

$$f=600\text{Hz}$$