MCQ Detailed View

A rainbow is one of the most beautiful natural phenomena, and its formation can be fully explained through the principles of optics. When sunlight interacts with water droplets in the atmosphere, three important phenomena of light are involved: refraction, dispersion, and total internal reflection.

1. 
   

   Refraction:
   When sunlight enters a raindrop, it bends at the boundary between air and water. This bending of light is called refraction. The angle of bending depends on the wavelength (or color) of the light.

   
   


2. 
   

   Dispersion:
   White light from the sun is a mixture of different colors. As it passes through the raindrop, the different wavelengths separate. Violet light bends the most, while red light bends the least. This splitting of light into its component colors is called dispersion, and it is responsible for the rainbow’s seven colors: red, orange, yellow, green, blue, indigo, and violet (ROYGBIV).

   
   


3. 
   

   Total Internal Reflection:
   After refraction and dispersion, the light rays hit the inner surface of the raindrop. Instead of passing out, they are reflected back inside due to total internal reflection. This happens when light inside the water droplet strikes the surface at a certain angle, causing it to reflect completely.

   
   

Finally, the reflected rays exit the droplet, undergoing refraction again, and reach the observer’s eye. The combined effect of these processes produces a bright, colorful arc in the sky opposite the sun.

Thus, the formation of a rainbow involves all three phenomena: refraction, dispersion, and total internal reflection.

👉 Correct Answer: All of the above