Page 45 - cbse-class-10-light-reflection-and-refraction

Even though all colors of the visible spectrum travel at the same speed in vacuum,
their speed varies when they pass through a transparent medium such as glass or
water. That is, the refractive index of glass varies depending on the color.

When a polychromatic light (multicolored or light with more than one
wavelength), such as white light, strikes the first surface of the prism, it is
refracted. However, each constituent of white light is refracted through a different
angle, causing white light to be dispersed. When these colors strike the prism's
second surface, they undergo refraction (being refracted from a denser to a rarer
medium) and are further separated. A white light beam incident on a prism splits
into its constituent colors, forming a spectrum.

Each component of the white light is deviated towards the prism's base. Violet has
the greatest deviation, while red has the least. The obtained spectrum is impure
because the colors in the spectrum lack sharp boundaries, i.e., each color merges
gradually into the next.

Recomposition of White Light

The prisms are arranged as shown in the diagram to produce white light from
dispersed light. Recomposition of white light is the recombination of the seven
colors of dispersed white light to produce white light.

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