Question 2: Why Wet Surfaces Appear Darker
Explanation
A dry, rough surface scatters light in all directions (diffuse reflection). This scattered white light mixes with the object’s color, making it appear paler or whitish.
When water covers the surface:
- Smoothing Effect: The water film creates a smooth interface, reducing the random scattering (diffuse reflection) at the surface.
- Impedance Matching: The refractive index of water is closer to that of the material than air is. This allows more light to penetrate the material rather than reflecting off the surface.
- Absorption: The light that enters undergoes multiple internal reflections within the water film and is absorbed by the material, making the surface appear darker and the color richer.
Correct Option: (a) Due to moistening, surface irregularities are covered with water film, which reduces diffused reflection of light.