Question

"The wavelength of light in a medium is

λ=λ0/μ, where λis the wavelength in vacuum. A beam of red light λ0=720 nmenters water. The wavelength in water is λ=λ0/μ=540 nm. To a person under water, does this light appear green?"

Answer 1

No, The person under water cannot see it as green light. Instead he sees as Red.

The wavelength of light in a medium is  λ=λ0/μ, where λ is the wavelength in vacuum.

red light λ0=720 nm

wavelength in water is λ=λ0/μ=540 nm.

Colour of light will depend only on the frequency of light and not on the wavelength of the light. So, light will appear red to an observer under water.

Answer 2

Question :-

"The wavelength of light in a medium is

λ=λ0/μ, where λis the wavelength in vacuum. A beam of red light λ0=720 nanometers water. The wavelength in water is λ=λ0/μ=540 nm. To a person under water, does this light appear green?"

Answer :

No the light will not appear green .

This is because the colour depends upon frequency.

Frequency depends upon the source of light and NOT on the wavelength .

This is the reason why light will still appear red.