Polarizers and Corn Syrup
| Chemistry, Physics: | Polarizers, Optically Active Materials |
| Grade Range: | Elementary School, Middle School, High School |
| Format: | Hands-on |
This demonstration is easy to set up, but can be hard to explain to younger students. Otherwise, it is a fun demonstration to play with, and easy to be mesmerized by!
Materials
- Large Polarizer
- Small Polarizers
- Cut Polarizers
- Glass Bottle of Corn Syrup
- Light Source (Small Lamp or Similar)
Safety Precautions
Please read the General Safety Precautions section of the Demonstration Safety page before performing this demonstration.
Demonstration
- Set the large polarizer in front of the light source. Set out the other polarizers and the corn syrup.
- As students come up, have them first hold one of the small polarizers and look through them at the ceiling lights. Do they see anything happening?
- Have students hold the small polarizers in front of the large one, and spin them. What do they see happening? Do they have any ideas for why?
- Let students try using the cut polarizers, and also try using the corn syrup inbetween the large polarizer and a small polarizer. What do they see happening? Why might that be?
Why This Works
Polarizers are transparent sheets which filter out half of the light coming through them. A polarizer will only let light through at a certain angle. When looking through a single polarizer, you might see some shadows and reflections change on objects. When you use two polarizers, you can see the second polarizer going completely dark when positioned at the correct angle. This is because the first polarizer is only letting light through at one angle, while the second is blocking that angled light!
When you look at the corn syrup or the cut polarizer, you will see colors coming through them instead of them turning dark. This is because the tape on the polarizer and the corn syrup are Optically Active Materials, or OAMs. OAMs are materials that have a mix of regular and mirrored molecules. Because they have a mix, instead of having either only regular or only mirrored molecules, these materials cause light to pass through them irregularly. This results in the wavelengths, or colors, of light passing through to exit at different angles! This is why, as you rotate a polarizer, the corn syrup or the taped polarizer will change colors!
Additional Information
- Encourage students to think about what kinds of things use polarizers. Examples are sunglasses, tinted windows, and computer screens.
- This demonstration pairs well with Invisible Glass, Color Mixing, and the Light Box.