JEE Main · 2022 · 25 Jul 2022 · Shift 1 · Geometrical Optics

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Which of the following statement is correct?
  1. (A)In primary rainbow, observer sees red colour on the top and violet on the bottom✓ Correct
  2. (B)In primary rainbow, observer sees violet colour on the top and red on the bottom
  3. (C)In primary rainbow, light wave suffers total internal reflection twice before coming out of water drops
  4. (D)Primary rainbow is less bright than secondary rainbow.

Answer: (A)

Solution

In a primary rainbow, light undergoes one internal reflection inside the water droplet. Due to dispersion and the geometry of refraction, red light (longer wavelength, less deviation) appears at the top of the arc and violet (shorter wavelength, more deviation) appears at the bottom. The primary rainbow is brighter than the secondary rainbow because less light is lost in a single internal reflection compared to two reflections in the secondary rainbow.

JEE Main · 2022 · 25 Jul 2022 · Shift 1 · Single correct option

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