What effect does a polarizing filter have on light?

A polarizing filter selectively allows light that is oscillating in a specific orientation to pass through while blocking light that is oscillating in other orientations. This means that when unpolarized light, which vibrates in multiple planes, encounters a polarizing filter, only the light waves aligned in the same plane as the filter will be transmitted. This characteristic makes polarizing filters useful in various applications, such as reducing glare from surfaces like water or roads, improving contrast in photography, and controlling reflections.

The effect described in the correct answer highlights the fundamental nature of how polarizing filters interact with light waves, specifically their ability to permit light in a single plane while filtering out others. By focusing on this aspect, it becomes clear that polarizing filters do not block all light completely, enhance brightness, or change the color of the light; instead, they provide a means to manipulate light based on its polarization state.