The phenomenon of rainbow formation by water droplets involves :

Correct option is D

The correct answer is (d) both refraction and internal reflection of sunlight. The formation of a rainbow involves multiple processes, including refraction, dispersion, internal reflection, and another refraction as light exits the water droplet. Here's how it works:
Refraction: When sunlight enters a water droplet, it bends due to the change in medium (air to water). This bending, or refraction, separates the light into its component colors because different colors have different wavelengths and bend at different angles (dispersion).
Internal Reflection: The light then reflects off the inside surface of the droplet. This internal reflection is crucial for directing the light back out of the droplet.
Refraction again: As the light exits the droplet, it undergoes refraction again, bending as it moves from water back to air. This second refraction further separates the light into the spectrum of colors we see in a rainbow.
Thus, the phenomenon involves both refraction and internal reflection of sunlight within the water droplets.
Information Booster: ● The colors of the rainbow are a result of dispersion, where light separates into its component wavelengths (red, orange, yellow, green, blue, indigo, and violet). ● Each color emerges at a different angle due to its wavelength, with red bending the least and violet the most. ● Secondary rainbows can form when sunlight undergoes two internal reflections, producing a fainter and inverted rainbow. ● Total internal reflection occurs when the light inside the droplet reflects without leaving, which is crucial for rainbow visibility. ● The angle of deviation for a primary rainbow is approximately 42 degrees from the direction opposite the light source. ● Rainbows are visible when the sun is behind the observer, and rain is falling ahead.