Question: 10: During a cloudy day, a primary and a secondary rainbow may be created, then the :
(1) primary rainbow is due to double internal reflection and is formed above the secondary one.
(2) primary rainbow is due to double internal reflection and is formed below the secondary one.
(3) secondary rainbow is due to double internal reflection and is formed above the primary one.
(4) secondary rainbow is due to single internal reflection and is formed above the primary one.
Answer: Option (3)
Explanation:
A rainbow is formed due to refraction, dispersion, and internal reflection of sunlight inside water droplets. In the primary rainbow, sunlight undergoes one internal reflection inside the droplet, resulting in a brighter rainbow that appears lower in the sky.
In the secondary rainbow, sunlight undergoes two internal reflections inside the water droplet.
Due to the extra internal reflection, the secondary rainbow is fainter and appears at a larger angle,
which makes it form above the primary rainbow.
Therefore, the secondary rainbow is due to double internal reflection and is formed above the primary rainbow.