Rainbow is produced when sunlight falls on drops of rain. Which of the following physical phenomena are responsible for this?
- ADispersion
- BRefraction
- CInternal reflection
- D1, 2 and 3Correct
Explanation
Rainbow formation is a beautiful demonstration of several optical phenomena. Here's a breakdown:
Refraction: When sunlight enters a raindrop, it slows down and bends (refracts) due to the change in medium (air to water). Different wavelengths of light bend at slightly different angles.
Dispersion: This difference in bending angles based on wavelength is called dispersion. It's why white sunlight splits into its constituent colors (VIBGYOR).
Internal Reflection: After refraction, the light travels to the back of the raindrop and reflects off the inner surface. This is total internal reflection.
These three phenomena – refraction, dispersion, and internal reflection – work together to create the rainbow we see. Therefore, option D, '1, 2 and 3', is the correct answer.
Why other options are incorrect:
A) Dispersion: While crucial, dispersion alone doesn't explain the entire process.
B) Refraction: Refraction initiates the process, but doesn't complete it.
C) Internal reflection: Internal reflection is a key step, but needs refraction and dispersion to create the spectrum.
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