Question

The splitting of white light into several colors on passing through a glass prism is due to:
A. Refraction
B. Reflection
C. Dispersion
D. none of these

Answer 1

Hint: When white light, composed of seven colors, enters a glass prism, it gets separated into a rainbow pattern according to the wavelength of different colors. This phenomenon occurs due to the difference in the degree of refraction experienced by several colors inside the glass prism.

Complete step by step answer:
Dispersion of white light is the phenomenon of splitting of white light into its constituent spectrum of colors, when it propagates through a glass prism. The figurative meaning of dispersion is distribution, and that’s what actually happens when light passes through glass dispersion; it gets distributed into its constituent colors – violet, indigo, blue, green, yellow, yellow, orange, and red. The white light gets splitted into its constituent colors at various frequencies and various angles.

Dispersion is a material property where the index of refraction is wavelength dependent. As the glass prism has positive dispersion, meaning the index of refraction will increase with the decrease in wavelength. As a result, shorter wavelengths undergo greater degree of refraction than the longer wavelengths.
In VIBGYOR pattern, red color has maximum wavelength, so it covers maximum distance inside the prism without deviation, but the violet color has minimum wavelength, so it gets spread inside the prism and deviates the most. We can say that Violet has the least velocity in the spectrum and it therefore undergoes maximum deviation while Red has the highest velocity in the spectrum and it therefore undergoes minimum deviation inside the glass prism.
Formula for angle of deviation inside glass prism:
$\delta =(\mu -1)A$
Where, $\mu $ is the refractive index offered by glass prism and $A$ is the angle of prism.
The splitting of white light into several colors on passing through a glass prism is due to the dispersion of light.
Hence, the correct option is C.

Note:
Angle of deviation inside glass prism depends on: Angle of incidence, Angle of prism, and Wavelength of light. The bending occurs during refraction because the light travels slower in a denser medium. The shorter wavelengths of light are slowed more in the denser medium such as prism, and therefore experience more bending than those with the longer wavelengths. The light which has the largest wavelength bends the least while the one with shortest wavelength bends the most.