Overview: Take your science skills into the kitchen. Turn ordinary chocolate into an edible optics demo that shows how diffraction works.
Supplies: Stove, double boiler, heat proof spatula, candy thermometer, diffraction sheets, silicon molds (optional), chocolate bars or melting chocolate
Objectives: Diffraction is the bending of light. We do not need to look through a diffraction sheet to see the bending. Light can bounce off of fine grooved surfaces to show us how each wavelength of light refracts off of the surface.
Setup:
If using molds, cut the diffraction sheets into pieces the size of the bottom of the molds. Place the diffraction pieces, diffraction side up, in the bottom of the mold
Divide your chocolate into thirds, 2/3 are for melting, 1/3 is for the tempering
Different chocolates have different tempering temperature, these temperatures are critical for proper tempering
Follow this video (starting at minute 20 for chocolate) on how to temper chocolate and create the diffraction pieces
If using molds, chocolate can be poured into molds quite easily
How to run the demo:
Pass out the chocolate and explain what they see.
Try this:
Follow the instructions in the video (starting at minute 7:40) to make diffractive candy
What’s Happening?
White light can be separated into all seven major colors of the complete spectrum or rainbow by using a diffraction grating. The grating separates light into colors as the light passes through the many fine slits of the grating. Each color travels at a different speed and therefore has a different angle of refraction when it hits the grating. Chocolate makes a reflection gratings. Along with chocolate, a compact disc also makes a good reflection grating. When light passes through a grating it is called a transmission grating. A transmission grating is what is used to make the diffractive chocolate. Diffractive candy is a transmission grating.
Learn more: (external links)