Explain the main physical processes that cause a rainbow to appear when sunlight passes through rain droplets.
Answer
A rainbow is formed by reflection, refraction and dispersion of sunlight in water droplets.
The correct answer is A rainbow is formed by reflection, refraction and dispersion of sunlight in water droplets. — The combination of these steps produces the circular rainbow observed.
Step-by-step solution
- Recall that sunlight enters a water droplet and is refracted.
- Inside the droplet, part of the light is reflected off the inner surface.
- The light then refracts again as it exits the droplet.
- Because water has different refractive indices for different wavelengths, the rays spread apart (dispersion), giving the sequence of colors.
- The combination of these steps produces the circular rainbow observed.
Common mistake: Attributing the rainbow solely to reflection or refraction.
Concept tested: Dispersion and rainbow formation
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