Question

Plane polarized light can be produced by the phenomenon of

• A. reflection
• B. dispersion
• C. diffraction
• D. scattering
• E. interference

Hint:

Remember Brewster's law: \[ \tan i_B = \mu \] At this angle, reflected light is completely plane polarized.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Plane polarized light is light in which the electric field oscillations are confined to a single plane. Unpolarized light consists of oscillations in all directions perpendicular to the direction of propagation. The question asks which of the given phenomena can be used to produce polarized light from unpolarized light.
Step 2: Detailed Explanation:
Let's analyze the options:

(A) Reflection: When unpolarized light reflects off a non-metallic surface (like glass or water), the reflected light is generally partially plane-polarized. At a specific angle of incidence, known as Brewster's angle, the reflected light is completely plane-polarized, with its electric field vector oscillating parallel to the reflecting surface. This is a standard method for producing polarized light.

(B) Dispersion: This is the splitting of white light into its constituent colors (spectrum) by a prism or grating. It does not cause polarization.

(C) Diffraction: This is the bending of waves as they pass around an obstacle or through an aperture. It is a property of all waves and does not produce polarization.

(D) Scattering: When light is scattered by small particles (like molecules in the atmosphere), the scattered light is partially polarized. For example, the blue light from the sky is polarized. While this is a valid method, reflection is also a valid and more direct method listed as an option. In many contexts, reflection is considered a primary method.

(E) Interference: This is the superposition of waves leading to reinforcement or cancellation. It does not cause polarization.

Both reflection and scattering can produce polarized light. However, reflection at Brewster's angle is a classic and definitive method for producing completely plane-polarized light. Given the options, reflection is a primary and correct answer.
Step 3: Final Answer:
Plane polarized light can be produced by the phenomenon of reflection. This corresponds to option (A).