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Difficulty: HardPhysics Fundamentals and Everyday Applications

Consider the following statements regarding optical phenomena observed in daily life:

1. Polarized sunglasses effectively reduce glare from horizontal surfaces such as water or asphalt because light reflected at Brewster's angle is predominantly horizontally polarized.
2. The white appearance of clouds, as opposed to the blue color of a clear sky, is attributed to Mie scattering by water droplets that scatter all visible wavelengths almost equally.
3. In the formation of a primary rainbow, sunlight undergoes two internal reflections and two refractions inside a raindrop, resulting in an inverted color sequence relative to a secondary rainbow.

Which of the statements given above is/are correct?

  1. 1 and 2 onlyAnswer
  2. B
    2 and 3 only
  3. C
    1 and 3 only
  4. D
    1, 2 and 3

Answer

Statements 1 and 2 are correct.
The option stating '1 and 2 only' is correct. Glare reduction in polaroids relies on blocking horizontally polarized light reflected off flat surfaces (Statement 1). Clouds appear white because large droplet diameters cause Mie scattering, which scatters all colors of light equally (Statement 2). Statement 3 is incorrect because a primary rainbow is formed by a single internal reflection combined with two refractions inside raindrops, whereas a secondary rainbow involves two internal reflections.

Step-by-Step Solution

1
Analyze Statement 1 regarding glare and polarization.
Statement 1 is TRUE.
When unpolarized light strikes a smooth horizontal reflecting surface (like water or wet roads) near Brewster's angle, the reflected light becomes polarized parallel to the surface (horizontally polarized). Polarized sunglasses contain vertically oriented polarizing filters that absorb this horizontally polarized light, effectively eliminating glare.
2
Analyze Statement 2 regarding cloud color and scattering type.
Statement 2 is TRUE.
Rayleigh scattering occurs when scattering particles are much smaller than the wavelength of light (d≪λ d \ll \lambda), selectively scattering shorter blue wavelengths. In clouds, water droplets are significantly larger than light wavelengths (d≥λd \ge \lambda), triggering Mie scattering, which scatters all visible light wavelengths nearly equally, causing clouds to appear white.
3
Analyze Statement 3 regarding rainbow optics.
Statement 3 is FALSE.
A primary rainbow is formed when sunlight enters a spherical raindrop, undergoes refraction upon entry, one internal reflection at the back of the droplet, and a second refraction upon exit (1 reflection, 2 refractions). A secondary rainbow involves two internal reflections and two refractions (2 reflections, 2 refractions), which also makes it fainter and causes its color order (red inside, violet outside) to be reversed compared to the primary rainbow.

Key Concept

Optical Phenomena in Daily Life (Polarization, Mie Scattering, and Rainbow Internal Reflection)
Estimated Time:2m 0s
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Topics

Physics Fundamentals and Everyday Applications

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