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Difficulty: MediumPhysics Fundamentals and Everyday Applications

Polaroid sunglasses are widely used to reduce glare from horizontal reflective surfaces such as wet asphalt roads and water bodies during sunny days. Which wave property of light is primarily utilized by polaroid lenses to eliminate this reflective glare?

  1. Polarization by reflection, where reflected light becomes predominantly horizontally polarized and is blocked by vertically aligned polarizing filters.Answer
  2. B
    Total internal reflection, which traps high-intensity reflected rays within the lens matrix, preventing them from reaching the eye.
  3. C
    Diffraction of light waves, which bends the glare around the perimeter of the pupil to decrease light intensity.
  4. D
    Dispersion of light, which separates the reflected glare into constituent spectral colors of lower individual brightness.

Answer

Polarization by reflection, where reflected light becomes horizontally polarized and is selectively absorbed by vertically aligned polarizing filters in the lenses.
When natural unpolarized light reflects off a flat horizontal surface, the reflected rays become polarized parallel to that surface (horizontally). Polaroid lenses feature vertically oriented transmission axes that selectively absorb this horizontally polarized glare while permitting useful ambient light to pass.

Step-by-Step Solution

1
Analyze the nature of unpolarized sunlight and its reflection off horizontal surfaces.
Unpolarized sunlight contains electric field oscillations in all planes perpendicular to the propagation direction. When it reflects off smooth non-metallic horizontal surfaces (like water or road asphalt), the electric field components parallel to the surface (horizontal plane) are preferentially reflected.
According to Brewster's law, at specific reflection angles, the reflected light becomes strongly linearly polarized in the horizontal plane.
2
Determine the operating principle of polaroid sunglasses.
Polaroid sunglasses are manufactured with their transmission axis aligned vertically.
Vertically oriented polarizing filters absorb horizontally polarized light waves while allowing vertically polarized ambient light to pass through, effectively cutting off the glaring reflections.

Key Concept

Polarization of Light and Brewster's Law
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Topics

Physics Fundamentals and Everyday Applications

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