Rainbow is produced when sunlight falls on drops of rain. Which of the...
Formation of rainbow involves all dispersion, refraction and internal reflection.

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Rainbow is produced when sunlight falls on drops of rain. Which of the...
Explanation:
To understand why a rainbow is produced when sunlight falls on drops of rain, we need to consider the physical phenomena of dispersion, refraction, and internal reflection.
1. Dispersion:
Dispersion refers to the phenomenon where light is separated into its component colors. When sunlight passes through a raindrop, it undergoes dispersion as the different wavelengths of light are refracted (bent) at different angles. This is due to the variation in the refractive index of the raindrop for different colors of light. Dispersion is responsible for the separation of the colors in a rainbow.
2. Refraction:
Refraction is the bending of light when it passes from one medium to another with a different refractive index. When sunlight enters a raindrop, it undergoes refraction as it transitions from air to water. The change in medium causes the light to change speed and direction. The different colors of light are refracted at slightly different angles, leading to the dispersion mentioned earlier. Refraction is responsible for the bending of light rays and the formation of a rainbow.
3. Internal Reflection:
Internal reflection occurs when light rays are reflected back into the medium from which they came, instead of being refracted out. Inside a raindrop, after refraction occurs, some of the light rays undergo internal reflection at the inner surface of the raindrop. These internally reflected rays then exit the raindrop, resulting in the formation of a rainbow. Internal reflection plays a crucial role in the creation of a rainbow.
Conclusion:
In summary, the correct answer is option 'D' - all three physical phenomena (dispersion, refraction, and internal reflection) are responsible for the production of a rainbow when sunlight falls on drops of rain. Dispersion separates the different colors of light, refraction bends the light rays, and internal reflection reflects the light back out of the raindrop, creating the beautiful colors we see in a rainbow.