The wavelength of light changes when it moves from one medium to another due to a change in its speed. The speed of light in any medium is given by
v=‌, where
v is the speed of light in the medium,
c is the speed of light in vacuum, and
n is the refractive index of the medium.
The wavelength of light in any medium can be related to its wavelength in vacuum by the equation:
λ‌medium ‌=‌=‌Given that the refractive index of air is approximately 1 (i.e.,
n‌air ‌≈1 ), we can use the given refractive index of the new medium (
n‌medium ‌=1.5 ) to find the new wavelength in that medium.
Let the wavelength of the light in air be
λ‌air ‌=600‌nm and in the new medium let it be
λ‌medium ‌. Substituting the given values into the equation, we get:
λ‌medium ‌=‌=400‌nmTherefore, the wavelength of the light in the new medium with a refractive index of 1.5 will be
400‌nm. Hence, the correct answer is Option D,
400‌nm.