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Brilliant colours in thin oil films on water: Identify the cause. Small oil films on water on a rainy day show vivid colours due to a wave-optics effect. Choose the correct option.

Difficulty: Easy

Interference of light in thin films (with reflection)
Diffraction from edges
Scattering by droplets (Tyndall effect)
Polarization by reflection

Correct Answer: Interference of light in thin films (with reflection)

Explanation:

Concept

Varying film thickness causes path difference between rays reflected from the top and bottom interfaces.
Constructive/destructive interference at different wavelengths produces colours.

Final Answer
Interference of light in thin films (with reflection)

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