Question

Draw a ray diagram to show the formation of a rainbow. Mark on it, points (a), (b) and (c) as given below: 
(a) Where dispersion of light occurs. 
(b) Where light gets reflected internally. 
(c) Where final refraction occurs.

Hint:

Rainbows occur due to the dispersion of light, which is then reflected internally inside water droplets before exiting and forming a spectrum of colors.

Answer 1

Rainbows form when sunlight bends and separates within atmospheric water droplets. The process involves these steps:
Light Dispersion (Step a): Sunlight enters a water droplet and bends, or refracts. Because different colors of light have different wavelengths, they refract differently, causing dispersion (splitting white light into its component colors).
Internal Reflection (Step b): After dispersion, light travels through the droplet and bounces off the inner surface. This internal reflection at the back of the droplet is why rainbows are curved.
Second Refraction (Step c): The light exits the droplet and refracts again, further separating the colors to create the visible spectrum (the rainbow). The rainbow we see results from many droplets refracting, reflecting, and refracting, each showing different colors at various angles.