Disappearing Color Wheel (Juliana Capra)
Author
Juliana Capra
Principle(s) Illustrated
Interactions of different colors of observed light
Differences between observed white light versus colored light
Standards
Middle School
MS PS 4-2: When light shines on an object, it is reflected, absorbed, or transmitted through the object, depending on the object's material and frequency (color) of the light.
MS PS 4-1: A simple Wave has a repeating patten with a specific wavelength, frequency, and amplitude
MS-PS4-2.
Develop and use a model to describe that waves are reflected, absorbed, or transmitted through various materials.[Clarification Statement: Emphasis is on both light and mechanical waves. Examples of models could include drawings, simulations, and written descriptions.] [Assessment Boundary: Assessment is limited to qualitative applications pertaining to light and mechanical waves.]
Questioning Script
Prior knowledge & experience:
Students understand that observed color is the interaction between the observer, the light absorbed, and light reflected from a source.
Root question:
Why is it that when the color wheel is stationary (not spinning) that the observer is able to see several colors but when the wheel is spinning the observer is unable to see all of the colors?
Why do the colors seem to disappear when the wheel is spinning?
Target response:
What people observe as white light is actually the interaction of all wavelengths of visible light. When we use a diffraction grating or a prism to "break up" white light we can see what colors of light white light is composed of.
When observing the spinning wheel we more or less observe the blending of several colors of light and it results in what we see as white light, so the colors on the wheel seem like they are disappearing.
Common Misconceptions:
The colors on to wheel are disappearing when you spin the wheel.
Photographs and Movies
Photos:
Step 1: Trace a circle with a flat round object onto a piece of white card stock paper, or a white side of a cereal box (lighter weight cardboard)
Step 2: Equally divide the circle into 6 sections using a ruler or straight edge
Step 3: Color each section with a different color, following the color wheel sequence of colors (Red, Orange, Yellow, Green, Blue, Violet) using coloring utensils such as markers, crayons, or colored pencils.
Step 4: Cut out the colored circle
Step 5: Repeat steps 1 through 5, creating a second circle
Step 6: Glue the two circles together, so that the colored sides are facing outwards.
Step 7: Using a small push pin or sharp object to poke two small holes near the center of the circle, making sure to poke through both circles.
Step 8: Cut a piece of string, about 36 inches in length. (Using a thicker string or yarn works best).
Step 9: Gently feed the string through each hole on the paper wheel. When you are done you should have two loops of string fed through on both sides of the color wheel. Tie a knot to secure the loose ends.
Step 10: To move the wheel and see the colors "disappear" hold both ends of the string hold both ends of the string, one with each hand. Using a motion similar to a jump rope, swing the wheel until the strings are twisted together. Then gently tug the string in opposite directions and the wheel should spin. This step will take some practice, so be patient!
References
Reference 1: Spangler Science page on how to create a disappearing color wheel with detailed instructions and diagrams.
http://www.stevespanglerscience.com/lab/experiments/disappearing-color-wheel
Reference 2: Physics classroom page on light waves, color, and their interactions
http://www.physicsclassroom.com/class/light/Lesson-2/Color-Addition
Reference 3: Exploratorium video explanation on white versus color light