Polarization 101

Explore how polarizers affect light!

10 minutes


  • Carefully review the general safety advice on the back of the box cover before starting the experiment.

Step-by-step instructions

The dark films in this set are polarizing filters. When you cross two filters at different angles, you can observe changes in transparency.


Let’s assemble a special construction to reflect the light from your cell phone’s flashlight.


As light reflects off of a plastic object, its properties change. So rotating the filter causes changes in brightness.


Unlike plastics, metal objects don’t affect light’s properties when reflecting it.



Dispose of solid waste together with household garbage.

Scientific description

You can think of light as a stream of tiny particles called photons. A simple lightbulb produces more than a billion billions of photons per second. The more photons meet our eyes, the brighter we perceive light to be.

Each photon has its own color and an attribute called polarization. Our eyes only “register” the quantity of photons and their colors, but not their polarization, so we can’t see it directly. The photons  from sunlight  and lamplight are produced in a mixture of all polarizations. This kind of light is called unpolarized light.

A polarization filter  “favors” a certain polarization and lets through only the photons  with this particular polarization. Other photons are either converted to the “favored” polarization or blocked entirely. The closer the photons are to the “favored” polarization, the easier it is for the filter to adjust them.

As a result, the photons that ultimately emerge from the filter all have the same polarization. This creates polarized light. If the filter is turned, it starts to “favor” another polarization. If one filter is placed over another, the difference in “favored” polarizations will affect the brightness of the light that passes through. The brightness of the light will change when you rotate one of the two filters.

Some materials partially polarize light as they reflect it. If you look at light reflected by such materials through a polarizer, the brightness of the light will change as you rotate the filter.