The wavelength of light diminishes `mu` times (`mu=1.33` for water) in a medium. A diver from inside water looks at an object whose natural colour is green. He sees the object as

Options

A. Green
B. Bule
C. Yellow
D. Red

Answer

To solve the problem, we need to analyze how the color of light is perceived when it travels through different media, specifically from water to air.

### Step-by-Step Solution:

1. **Understanding Wavelength and Frequency**:
- Light has a certain wavelength and frequency. The color of light is primarily determined by its wavelength. However, when light travels from one medium to another, its speed and wavelength change, but its frequency remains constant.

2. **Refractive Index**:
- The refractive index (µ) of a medium is defined as the ratio of the speed of light in a vacuum to the speed of light in that medium. For water, µ = 1.33. This means that the wavelength of light in water is reduced by a factor of µ compared to its wavelength in a vacuum.

3. **Color Perception**:
- When a diver looks at a green object underwater, the light reflecting off the object enters the water. The green color corresponds to a specific wavelength of light. As the diver looks at the object, the light travels from the water to the air.

4. **Effect of Medium Change**:
- When light exits the water and enters the air, its wavelength increases back to its original value (in a vacuum). However, the frequency of the light does not change during this transition. Since color perception is more closely related to frequency than to wavelength when light transitions between media, the perceived color will remain the same.

5. **Conclusion**:
- Since the frequency of the light does not change as it travels from water to air, the diver will still perceive the green object as green.

### Final Answer:
The diver sees the object as green.