Short Question Answers

Q1. Explain the formation of a rainbow.

Ans. Rainbow:This is a phenomenon due to combined effect of dispersion, refraction and reflection of sunlight by spherical water droplets of rain.

1. Firstly, light refracted into from air to rain droplet.
2.Secondly, refracted ray get reflected in rain droplet internally.
3.Thirdly, after reflection again light refracted into from rain droplet to air , During this light get dispersed.according to order of wavelengths red is deviated less and emerges at angle $42^0$, violet is deviated more and emeges $40^0$.For other colours, angles lie in between these two values.

The secondary rainbow is also formed due to double internal reflection of sunlight in the rain drops.

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