describe the refraction taking place in the rainbow formation

CBSE Class 10 Answered

describe the refraction taking place in the rainbow formation

Asked by 0 0 | 19 Oct, 2023, 03:51: PM

Expert Answer

The rainbow is an example of the dispersion of sunlight by the water drops in the atmosphere. This is a phenomenon due to combined effect
of dispersion, refraction and reflection of sunlight by spherical water droplets of rain. The conditions for observing a rainbow are that the sun
should be shining in one part of the sky (say near western horizon) while it is raining in the opposite part of the sky (say eastern horizon).
An observer can therefore see a rainbow only when his back is towards the sun.

In order to understand the formation of rainbows, consider the given figure above. Sunlight is first refracted as it enters a raindrop, which
causes the different wavelengths (colours) of white light to separate. Longer wangelength of light (red) are bent the least while the shorter
wavelength (violet) are bent the most. Next, these component rays strike the inner surface of the water drop and get internally reflected

if the angle between the refracted ray and normal to the drop surface is greater then the critical angle (48º, in this case).

The reflected light is refracted again as it comes out of the drop as shown in the figure. It is found that the violet light emerges

at an angle of 40º related to the incoming sunlight and red light emerges at an angle of 42º. For other colours, angles lie in
between these two values.

Answered by Thiyagarajan K | 20 Oct, 2023, 03:48: PM