Question

The primary purpose of using polaroids in sunglasses is to

• A. make the sunglasses look fashionable
• B. change the colour of the objects
• C. control the intensity of light from the objects
• D. magnify the object
• E. make the sunglasses cheaper

Hint:

Polarized sunglasses are especially useful for drivers and boaters because they specifically target reflected glare from roads and water surfaces.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Polaroids (polarizing filters) act on the wave nature of light, restricting the plane of vibration of the electric field to a single axis.
Step 2: Key Formula or Approach:
Recall the theoretical application of polarization:
When unpolarized sunlight reflects off horizontal surfaces (like water or roads), it becomes partially horizontally polarized (glare). Polaroids oriented vertically block this specific reflected light.
Step 3: Detailed Explanation:
Let's evaluate the given options:
(A) Fashion is a byproduct, not the primary functional purpose.
(B) Polaroids do not change frequency or wavelength, so they do not fundamentally change true color.
(C) By blocking specific planes of polarization (especially horizontal glare), they significantly reduce the intensity of blinding light reaching the eyes.
(D) Polaroids have no refractive power; they do not magnify.
(E) Polarizing filters actually make lenses more expensive to manufacture, not cheaper.
Step 4: Final Answer:
The primary purpose is to control the intensity of light.