Final answer:
Components of light are resolved into a plane perpendicular to the upper polarizer, as only the light wave components parallel to the polarizer's axis are transmitted, and no light passes when the second polarizer's axis is perpendicular to the first.
Step-by-step explanation:
The components of light are resolved into a plane perpendicular to the upper polarizer. When light passes through a polarizing filter, only the components of the light wave that are parallel to the axis of the filter are transmitted. If there is a second polarizing filter placed above the first, and its axis is rotated, the amount of light passing through will change. When the axis of the second polarizer is perpendicular to the first, no light is passed, demonstrating that the light that originally passed through the first filter was polarized parallel to its axis.