Rainbow is an example of which phenomenon?

The correct option is Dispersion and total internal reflection.

A rainbow is a beautiful meteorological phenomenon caused by the interaction of sunlight with water droplets suspended in the atmosphere. This process involves three main optical events: refraction, dispersion, and internal reflection.

1. Refraction and Dispersion (Splitting of Light):
When sunlight enters a spherical raindrop, it passes from air (a less dense medium) into water (a denser medium). This change in medium causes the light to bend, a process known as refraction. Since sunlight (white light) consists of a spectrum of different wavelengths (colors), each color bends by a slightly different angle because water has a different refractive index for each wavelength. Violet light bends the most, while red light bends the least. This separation of white light into its constituent colors is called dispersion.

2. Total Internal Reflection (Reflection inside the drop):
After entering the raindrop and dispersing, the separated colors travel through the droplet and hit the back inner surface of the water droplet. If the angle of incidence at this back surface is greater than the critical angle for the water-air interface, the light does not exit the back of the droplet. Instead, it undergoes total internal reflection (or internal reflection) off the back wall, bouncing back inside the droplet toward the front surface.

3. Final Refraction:
Finally, the reflected light reaches the front surface of the droplet again and exits back into the air. As it exits from water to air, it refracts once more, further dispersing the colors and directing them towards the observer's eyes, forming the vibrant arc of a rainbow.

Thus, the formation of a rainbow is primarily an example of dispersion and total internal reflection (along with refraction) occurring within water droplets.