Question

Choose the right answer from the following.
We use flight glass prism to disperse polychromatic light because of light of different colors:
A. Travel at the same speed.
B. Travel with the same speed but deviate differently due to the shape of a prism.
C. Have different anisotropic properties while traveling through a prism.
D. Travel at different speeds.

Answer 1

In this question use the concept that different colors of light have different wavelengths so the speed of light will be different in different colors as the speed is dependent upon the wavelength of the color which is passing through a medium.

Complete step-by-step solution:
When the light travels in different mediums frequency remains the same but the wavelength is different for a different color of lights. The different colors of light all travel at roughly the same speed in the air. Hence, the option ‘A’ is incorrect.
In the glass, however, this is not true. Blue light gets slowed down by glass more than red light. As a result of their different speeds in the glass, the red and blue light gets bent at different angles when they go into the prism. This separates blue from red, and in fact, it separates all of the colors we can see. Hence, the option ‘B’ and ‘D’ is incorrect.
Flint glass prism has a high refractive index and there is high dispersion of light through it. If we take VIBGYOR, all colors have different anisotropic properties. We use a flight glass prism to disperse polychromatic light because the light of different colors has different anisotropic properties while traveling through the prism.
Hence, the option ‘C’ is correct.

Note: A White light is composed of primarily seven main colors that are VIBGYOR namely violet, indigo, blue, green, yellow, orange, and red. Red has the largest wavelength and the order of wavelength follows - red>orange>yellow>green>blue>indigo>violet. Amongst these colors blue is the most scattered color and that’s why the color of the sky is blue.