Light is polarized when its electric field vibrations are restricted to a single plane. Normally, light from natural sources like the sun or a bulb is unpolarized, meaning the light waves vibrate in multiple directions perpendicular to the direction of travel. Polarization filters or certain physical interactions can filter out specific directions of vibration, resulting in polarized light.
Methods of Polarizing Light:
- Polarization by Reflection
When light reflects off non-metallic surfaces (like water, glass, or roads), it becomes partially or completely polarized, especially at a specific angle known as Brewster’s angle. - Polarization by Transmission
Materials like Polaroid filters only allow vibrations in one direction to pass through. Light passing through becomes linearly polarized. - Polarization by Scattering
When sunlight passes through the atmosphere, it is scattered by air molecules. The scattered light becomes polarized, especially at 90° to the direction of the sun. - Polarization by Refraction
Certain crystals (like calcite) can split a light beam into two polarized beams, a process called birefringence. - Polarization by Double Refraction
Anisotropic materials (which have different properties in different directions) can polarize light by splitting it into two beams with orthogonal polarization directions.
Types of Polarization:
- Linear Polarization: Vibrations occur in a single plane.
- Circular Polarization: Electric field rotates in a circle as it travels.
- Elliptical Polarization: A general form where the electric field traces an ellipse.
Conclusion: Polarization filters or interactions like reflection, scattering, or birefringence limit the direction of light wave vibration, converting unpolarized light into polarized light.