27. NCERT Exemplar XIV

1. Why do we see a rainbow in the sky only after rainfall?

 

refractionDispersionreflection of sunlight by tiny water droplets present in the atmosphere lead to the formation of rainbow.

 

A rainbow is continually set in a direction oppositesame to that of the Sun. The water droplets behave like small prisms. They get refractedreflected and reflectdisperserefract the incident sunlight, then internally it gets reflecteddispersedrefracted, and finally, get refracted again when it comes out of the raindrop.

 

2. Why is the colour of the clear sky blue?

 

Blue colour in the white light suffers maximumminimum scattering. Due to this, it is the blue colour which reaches our eyesdoes not reach our eyes. This is the reason why makes the sky appears blue