Summer experiments with the Kitchen Pantry Scientist

EDINA, Minn. -- Liz Heinecke specializes in bringing science down to earth as The Kitchen Pantry Scientist. Her soon-to-be-published book, "Kitchen Science Lab for Kids" is filled with experiments to teach kids how the world works by using common items found in the home.

That includes a lesson on sunsets. Why do we see those beautiful red orange skies only when the sun is setting, or rising?

You'll need a wide container of water, milk, a flashlight and a white background. Liz says the pretty colors at dawn and dusk come from the particles in the atmosphere absorbing and reflecting light. Light contains all colors of the rainbow. Blue light has a shorter wavelength and more easily bounces off surrounding particles, like pollution.

That means the blue light scatters more easily. When the sun rises and sets, the light travels a longer distance across the atmosphere. By the time you see it, much off the blue in the light is scattered out, leaving the red, yellow and orange light behind.

You can see that by putting your clear container of water in front of a white surface. Shine the flashlight through it, and you will see mostly white light on the white background. Mix a few drops of milk into the water. Now shine your light -- you will see more yellow, orange and red light on that white background. The blue light has scattered because of the particles in the water.

In a second experiment, Liz illustrates how light can travel down a narrow beam of water, much as it might travel down a narrow tube, as it does with fiber optics.

For this experiment, you will need a clear bottle of water, a pin and a laser pointer.

Using your pin, make a small hole in the side of the bottle of water. You will want to put a bowl out to catch the narrow stream of water that will come out. Then, take your laser pointer, and shine it from the back side of the bottle through that hole where the water is coming out. You should see that laser light traveling part way down the stream of water, actually bending with the water.

Liz says there is a change in the speed of light at the boundary between air and water. When light from the laser beam travels near the boundary at a shallow angle, it is reflected back into the water. Liz says this is the same physics that carries light through optical fibers.

Want more experiments? Check out Liz's website, The Kitchen Pantry Scientist.


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