The wavelength of light in water decreases n times (n is the refractive index of water relative to air). Does this mean that the diver underwater cannot see the surrounding objects in natural light?
The wavelength of light decreases in water, but the frequency of the light wave remains the same, and the diver sees objects under water in natural light. Let’s pay attention to the fact that the refractive index of water is approximately equal to the refractive index of the lens of the eye, therefore, its optical power decreases, the focal length increases, and the eye becomes farsighted. Since the wavelength in water and in the eye changes in the same way, he sees the surrounding objects in natural light.
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.