Step 1 : Understanding the Question:
The topic of this question is Wave Optics, specifically focusing on the phenomenon of Polarization. Light exhibits various properties such as interference, diffraction, and polarization. While interference and diffraction confirm that light behaves like a wave, they do not distinguish whether those waves are longitudinal or transverse. Polarization is a unique property that restricts the vibrations of a wave to a specific plane. This question asks what this specific property reveals about the physical nature of light wave oscillations.
Step 2 : Key Formulas and approach:
The approach is conceptual rather than mathematical. It involves understanding the geometric constraints of different wave types:
1. Longitudinal Waves: Vibrations occur parallel to the direction of propagation (like sound). These are symmetrical around the axis of travel.
2. Transverse Waves: Vibrations occur perpendicular to the direction of propagation (like waves on a string).
3. Polarization Rule: Only waves with vibrations perpendicular to the direction of travel can be restricted to a single plane.
Step 3 : Detailed Explanation:
Longitudinal waves, such as sound waves in air, consist of compressions and rarefactions where particles move back and forth along the path of the wave. Because their motion is always along the direction of travel, there is no "side" to filter out; therefore, they cannot be polarized.
Transverse waves, however, have oscillations that occur in a plane perpendicular to the direction of the wave's velocity. These oscillations can be up-down, left-right, or at any angle in that perpendicular plane.
Polarization is the process of filtering these oscillations so that they only occur in one single direction (e.g., only vertical).
Experimentally, light can be polarized using materials like Polaroid filters or through reflection at specific angles (Brewster's Angle).
The fact that we can successfully block light by rotating two polarizers (cross-polarization) proves that light must have a specific orientation of oscillation that is perpendicular to its travel.
Thus, the ability of light to be polarized is the definitive evidence that light is a transverse wave.
Other phenomena like interference happen for both longitudinal and transverse waves, so they do not provide this specific proof.
Step 4 : Final Answer:
Since polarization is only possible for waves with perpendicular oscillations, it proves that light waves are Transverse. The correct option is (B).