Light: Linear polarizer

What causes light waves to become polarized?

  Light consists of an electric field wave and a magnetic field wave traveling together in phase, and therefore is often refered to as an electromagnetic wave. The electric and magnetic fields are always perpendicular to each other and the direction in which the wave is traveling. The polarization of light refers to how the electric field in a light (electro-magnetic) wave oscilates. Once we know what the electric field waveis doing, we can readily determine the behavior of the magnetic field wave, but when we discuss the polarization of light we will only worry about the electric field. In linearly polarized light, the electric field of the wave at any given point oscillates back and forth along a straight line. Unpolarized (electric field points in random direction in space and time) or elliptically/circularly polarized (electric field traces out an ellipse/circle in space and time) light waves can become linearly polarized when they travel through some materials, or when they are reflected from some surfaces. Some materials absorb or reflected strongly along one linear axis, which means that there will be strong differences in the amount that certain linear polarizations are transmitted and reflected. Imagine a material that only transmits light if it is polarized along one particular axis (along the lines in the polarizer in the simulation below. Both vertically and horizontally polarized light are incident on the polarizer, but only the component that is parallel to the polarizer's axis will get through. Rotate the polarizer angle in the simulation below to see what happens to the transmitted light. Note that the incident horizontal and vertical linearly polarized waves are shifted from each other by 90 degrees. What would happen if they were in phase with each other?

Use the above simulation to answer the following questions?