A source of sound of frequency 600 Hz is placed inside water. The speed of sound in water is `1500 m//s` and in air it is `300 m//s`. The frequency of sounds recorded by an observer who is standing in air is :-

Options

A. 200 Hz
B. 3000 Hz
C. 120 Hz
D. 600 Hz

Explanation

To solve the problem, we need to understand the behavior of sound waves as they travel through different media.

### Step-by-Step Solution:

1. **Identify the Given Information**:
- Frequency of the sound source (f) = 600 Hz
- Speed of sound in water (v_water) = 1500 m/s
- Speed of sound in air (v_air) = 300 m/s

2. **Understand the Concept of Frequency**:
- Frequency (f) is a property of the sound source and does not change when sound travels from one medium to another. This means that regardless of the medium (water or air), the frequency of the sound produced by the source remains constant.

3. **Conclusion**:
- Since the frequency of the sound source is 600 Hz, the frequency of the sound recorded by an observer standing in air will also be 600 Hz.

### Final Answer:
The frequency of sounds recorded by an observer who is standing in air is **600 Hz**.

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