The phenomenon of splitting white light into seven colours is called?
Dispersion
The explanation for the correct option:
Dispersion:
When white light passes through a glass prism, it splits into its spectrum of colors (in order violet, indigo, blue, green, yellow, orange, and red), and this process of splitting white light into its constituent colors is known as dispersion.
Hence, option(D) is correct.
The explanation for incorrect options:
Reflection:
The reflection of light occurs when a light ray approaches a smooth polished surface and bounces back.
Refraction:
It is a deflection from a straight path taken by a light ray or energy wave as it passes obliquely from one medium (such as air) into another (such as glass) with a different velocity.
Refractive index:
The refractive index (index of refraction) is a value calculated by dividing the speed of light in a vacuum by the speed of light in the second medium of greater density.
Thud, options (A),(B), and (C) are incorrect.
Hence, option(D) is correct.