Q48 / 56 · KVPY 2018 (SA) · Physics

Select the correct statement about rainbow.

  • A
     We can see a rainbow in the western sky in the late afternoon
  • Correct answer
    B
     The double rainbow has red on the inside and violet on the outside
  • C
     A rainbow has an arc shape, since the earth is round
  • D
     A rainbow on the moon is violet on the inside and red on the outside

Solution

In late afternoon rainbow is visible in east side when light of sun in west side is reflected and refracted by a layer of water droplets. Rainbow is circular because locous of reflected rays reaching eye of observer is a circle. Its roundness is not due to roundness of earth.
There is no rainbow on moon due to lack of atmosphere. In case of a primary rainbow, violet colour is on inside and red colour is on outside of arc. In case of a secondary rainbow, red colour is on inside and violet colour is on outside of arc.

Figure

So, none of the option is correct. Option
(b) is correct, if only secondary rainbow is considered.

Hence, the correct answer is option: 'B'.

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