Question

1. identify and describe five properties of polarization?

2. describe the three different ways light polarize.

Answer 1

1) Polarization is a phenomenon peculiar to transverse waves, i.e., waves that vibrate in a direction perpendicular to their direction of propagation. Light is a transverse electromagnetic wave (see electromagnetic radiation ). Thus a light wave traveling forward can vibrate up and down (in the vertical plane), from side to side (in the horizontal plane), or in an intermediate direction. Ordinarily a ray of light consists of a mixture of waves vibrating in all the directions perpendicular to its line of propagation. If for some reason the vibration remains constant in direction, the light is said to be polarized

2)Polarization by Reflection
Polarization by Scattering
Polarization by Refraction

if light strikes an interface so that there is a 90o angle between the reflected and refracted rays, the reflected light will be linearly polarized. The direction of polarization (the way the electric field vectors point)is parallel to the plane of the interface.The special angle of incidence that produces a 90o angle between the reflected and refracted ray is called the Brewster angle,

The scattering of light off air molecules produces linearly polarized light in the plane perpendicular to the incident light. The scatterers can be visualized as tiny antennae which radiate perpendicular to their line of oscillation. If the charges in a molecule are oscillating along the y-axis, it will not radiate along the y-axis. Therefore, at 90° away from the beam direction, the scattered light is linearly polarized. This causes the light which undergoes Rayleigh scattering from the blue sky to be partially polarized.

Polarization can also occur by the refraction of light. Refraction occurs when a beam of light passes from one material into another material. At the surface of the two materials, the path of the beam changes its direction. The refracted beam acquires some degree of polarization. Most often, the polarization occurs in a plane perpendicular to the surface. The polarization of refracted light is often demonstrated in a Physics class using a unique crystal that serves as a double-refracting crystal. Iceland Spar, a rather rare form of the mineral calcite, refracts incident light into two different paths. The light is split into two beams upon entering the crystal.