Question

rainbow has 7 colours or we see rainbow in rainy day give reason

Answer 1

because of the dispersion of white light we see the rainbow with seven colours.

Answer 2

heya!
here's your answer!


➡ before knowing why rainbow is seen, we must know what is the action of a prism:-

Here's it:-
➡yes , when a beam of white light is passed through a hollow prism .. it refracts to produce the spectrum of 7 colours .

➡ the spectrum includes
◾V- violet \
◾I - indigo \
◾b - blue \
◾g - green l ⏩ this is called Vibgyor
◾y - yellow /
◾o - orange/
◾r - red /

➡ this happens because the two faces of the prism act together like a glass slab .. which does not reflect light

➡ rather refracts it - now if you pass a spectrum through the prism - a clear beam of white light will come out from it

➡ but you must be thinking why this happens?
well .. this happens because when you combine these 7 colours can, white will be formed

➡ we're able to see the layers of the colours Because all the colours have different wavelengths and refractive indexes

Now,
The raindrops of water act like glass prism and hence they disperse white light of the sun into seven colours of the rainbow as explained above.

Hence we see all those seven colours of the rainbow and that is why Rainbow is formed.


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HOPE THIS HELPS YOU:)