SIMPLE SCIENCE
EXPERIMENTS
Here are three impressive demonstrations that, when mastered, look like magic.
GLOWING GOO
Objective: Create a glowing psychedelic substance that turns solid and then liquid again.
What You’ll Need:
•Cornstarch or potato starch
•A large mixing bowl and stirring spoon
•Sugar-free tonic water
•A black light
What to Do:
1. Add ½ cup of starch to mixing bowl.
2. Slowly add about ½ cup tonic water while stirring (with a spoon or your finger).
3. Continue combining the starch and water until you have the right consistency. The ratio should be about 1:1. Your goal is to form a liquid that turns solid when you tap it or move it around.
4. Turn off all the lights except for the black light, and start playing with your goo. Swiftly form it into a solid ball in your hands, and the instant you stop moving, it will liquefy and fall back into the bowl.
5. When you’re finished playing, slowly pour the goo in the sink along with a lot of water so it becomes diluted and doesn’t clog the drain.
The Science Explained: You’ve just created a non-Newtonian fluid. A Newtonian fluid, first described by Sir Isaac Newton, has the same viscosity—the ease with which it flows—whether it’s at rest or in movement. The most popular Newtonian fluid: water. The viscosity of a non-Newtonian fluid depends on the amount of force applied to its interconnected molecules. With your glowing goo, if force is applied quickly, the molecules don’t have enough time to “get out of the way,” and they remain bonded. But if the molecules are at rest, they don’t offer much resistance and you can slip right through them. Not all non-Newtonian fluids act this way. Ketchup does the opposite: shake it and it liquefies; leave it be and it behaves like a solid. Another non-Newtonian fluid: Silly Putty. Apply a small amount of force and you can shape it; apply a lot of force and it bounces (and then you have to find it).
Not a bunny: A baby rabbit is called a kitten.
This glowing goo experiment works the same with starch and regular water; it just doesn’t glow. The tonic water makes it more fun because it includes quinine, a nontoxic substance that glows under a black light. Why use diet tonic water? There’s no sticky sugar in it.
Bonus: Increase the amount of water and starch until you have enough to fill a wading pool. Slowly step in, and your foot will immediately sink to the bottom, but if you run across it really fast, you’ll stay on the surface.
THE VANISHING TEST TUBE
Objective: Make a piece of glassware invisible.
What You’ll Need:
•A large, transparent pitcher. Pyrex is preferred, but you can use any large vessel.
•A Pyrex test tube, or a smaller beaker made of Pyrex. (You may already have these—check your glass measuring cups. If they’re Pyrex, then you can get started. You may even have a glass bowl made of Pyrex. Otherwise, you can find Pyrex beakers at any specialty kitchen store. But if you can get ahold of a Pyrex test tube, that gives this experiment the biggest “wow” factor.)
•100% pure blended vegetable oil
•A small funnel (if necessary)
What to Do:
1. Fill the large pitcher about ⅔ to ¾ full with vegetable oil.
2. Place the smaller beaker or test tube inside it.
3. If the smaller Pyrex vessel is submerged completely, it will disappear. If you have a test tube, then use the funnel to pour oil into the test tube and watch it disappear!
The Science Explained: This experiment demonstrates an interesting property of refraction. You don’t really “see” glass. When light rays travel through glass, because it’s a different medium than air, the light rays change direction, distorting the appearance of objects on the other side. That’s refraction. It’s what makes your legs look really funny in a pool. The refractive index refers to the speed at which light rays bend. It just so happens that Pyrex glass and vegetable oil both have the same refractive index: 1.147. (Pyrex is the brand name of borosilicate glass, which is used for both laboratory glassware and kitchenware.) So when the light rays travel through the oil, and then through the oil-filled glass, they don’t change speed or bend. Because there are no hard edges on the tube, it seems to vanish completely.
Most popular singer in Kenya: Kenny Rogers.
Objective: Use static electricity to alter the course of falling water.
What You’ll Need:
•A plastic comb
•A sink
What to Do:
1. This experiment works best with low humidity, so don’t do this with wet hair, or in a bathroom right after someone has taken a shower.
2. Turn on the sink so the water flows in a small but steady stream less than a centimeter wide.
3. Comb your hair for at least 10 seconds. (If you’re Uncle John, you’ll need to find an assistant with hair. Otherwise, rubbing a balloon on your bald head will work.)
4. Place the teeth of the comb (or the balloon) about an inch away from the faucet, and the stream of water will bend toward it. (If it doesn’t, comb your hair some more, or reduce the flow from the faucet.)
The Science Explained: Static electricity is defined as “an electric charge that has accumulated on an object.” The plastic comb is made of atoms that are surrounded by charged electrons. The act of combing disrupts the electrons in your hair, and they “jump” from the hair to the comb. The hair that lost the electrons now has a positive charge, whereas the comb that gained the electrons has a negative charge. Meanwhile, the stream of water has both positive and negative electrons, giving it a neutral charge. Just as it is with magnets, opposites attract. So when the negatively charged comb gets close enough to the water, the positive electrons in the water are attracted to the buildup of negative electrons, and that attraction pulls the entire stream of water toward the comb.
Bonus: Have you noticed that during some times of the year—usually in the fall—you get shocked a lot more by static electricity? That’s because the relative humidity is low. As you walk around (especially if you shuffle your feet), you build up static electricity. With no moisture in the air to dissipate that charge, it keeps building and building until you touch a doorknob or a car latch…and then—ZAP!—you’ve been shocked by science!
“You cannot teach a man anything; you can only help him discover it in himself.”
—Galileo
According to Toyota, the plural of Prius is Prii.