Question

While the sunset when sun appear red , as only red wavelength comes, when we place a prism and allow it to pass through it, will it refract or disperse?

Answer 1

Hello,
Even if the scattering of light takes place at sunset and sunrise,The sunlight still is a spectrum ie..,white light.The fact that we see it red is not because it has only red wavelength.But because other rays have lost a lot of energy due to scattering ,so we see the dominant red only.
Also dispersion is only a subcase of refraction.Dispersion is caused due to refraction of lights.Since each wavelength has different speed inside prism ,they are refracted at different angles and thus we see splitting of colours.
On passing a rays from setting sun through a prism ,in reality the waves of different colour do split(dispersion) but due to their low intensity we may only see red ( as refraction of red only).
But actually dispersion is also happening