Rainbow Experiments

Brighten their day with the science of light and colors.

By Sarah Pottieger
Feb 26, 2015



Feb 26, 2015

Rainbow Jar

1. Have your child pour ½ cup of the following, in this order, into a glass jar: honey, corn syrup (mixed with purple food dye), green dish soap, and water (mixed with blue food dye). Top with 1 cup olive oil. Be sure she pours each liquid into the middle of the jar, not down the side.
2. With a dropper, squeeze ½ cup rubbing alcohol (mixed with red food dye) along the sides of the container; apply the drops in a circular motion.
3. As you admire the rainbow, explain that the liquids form layers because they have different weights, or densities. Heavier liquids sink below lighter ones. Have your child guess which one is heaviest.
4. Next, have kids guess how far different materials will sink into the layers. Experiment with paperclips, plastic beads, and pennies. Your child will see that some objects sink faster than others, and the beads won't even make it to the bottom! This demonstrates that solids have different densities, just like liquids.


DIY Prism

1. Fill a clear bowl with water. Carry it into a room with white walls.
2. Place a small mirror (a compact makeup mirror works well) along the inside of the bowl, so it's at a 45° angle. (You can prop it up with a small ball of clay.) Draw the shades (or turn off the light).
3. Aim a flashlight at the mirror and watch for the rainbow to appear on the opposite wall. (You may have to adjust the angle of the light or mirror to create the rainbow.)
4. Explain that when light travels in a straight line, it's white or clear. But when light “bends,” or is refracted, as it bounces off the mirror and through water, it separates into the colors of the rainbow.


Sugar Rush

1. Fill a shallow glass dish with enough water to cover the bottom.
2. Drop four different-colored Gobstoppers (aka jawbreakers) along the edge of the bowl, equidistant from one another.
3. Surprise! Instead of blending together, the colors will bleed into the middle, then stop.
4. After your child observes what's happening, explain: As the candy molecules dissolve into the water, the water changes hue. But since each candy is coated with wax, which isn't water-soluble, the wax layer stops the colors from running together.
5. Try the experiment with hot water, or a different liquid, to see if you get different results.


Photo Credit: TK

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