In the absence of a prism, what is making the photons in a rainbow congregate into bands of separate colors?

Question

And why are the colors are always in ROYGBV order?

In: 5

Answer 1

So, in high school physics classroom they will teach you about “refractive index” and how that number is useful for calculating the angle of refraction. For example light would go from air to water and enter the water at X angle, then ask at what angle would the light keep travelling underwater. You can only answer this question if you know the refractive index *n*

Now what I’m not aware of being taught in high school physics classrooms is this small detail about this *n* value and that is that *n* is a different value for different wavelengths. You have the same optical medium (air, water, etc.), but how dense these media are (i.e what exact number they have) depends on the wavelength. This dependence is why most (but not all) of white light separates in nature into a rainbow. I mean, dispersion (this rainbow effect) is taught, but not that it’s because *n* is wavelength dependent.