Corner Reflector - See yourself as others see you!

   Corner Reflector  See yourself as others see you.   Two hinged mirrors create a kaleidoscope that shows multiple images of an object. The number of images depends on the angle between the mirrors. When you set the hinged mirrors on top of a third mirror, you create a reflector that always sends light back in the direction from which it came.   Three 6 x 6 inch (15 x 15 cm) mirrors. Plastic mirrors are best, since there is less danger of breaking the mirror or cutting your fingers. Plastic mirrors are available at plastics supply...

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Cool Hot Rod - Objects change size when heated or cooled

Cool Hot Rod  Objects change size when heated or cooled   Changes in temperature cause objects to expand or contract. You may have noticed the effects of this kind of change around your house. If you run cool water on a hot glass, it may break, as some parts of the glass contract more rapidly than others. You can loosen a tight jar lid by running hot water over it, causing the metal lid to expand more than the glass. The expansion and contraction of materials when they are heated or cooled is commonly used to make thermometers and thermostats. This Snack allows you to directly observe...

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Convection Current - Make your own heat waves in an aquarium

    Convection Current  Make your own heat waves in an aquarium. This demonstration gives you a simple and visually appealing way to show convection currents in water. Warmer water rising through cooler water creates turbulence effects that bend light, allowing you to project swirling shadows onto a screen.   One 6- or 12-volt lantern battery or a suitable low-voltage battery eliminator or power supply.A pencil lead.A clear plastic or glass container with rectangular flat sides. (A small aquarium works fine.)A light source. (Slide projectors,...

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Condiment Diver - The world's simplest Cartesian diver

  Condiment Diver  The world's simplest Cartesian diver Squeezing a plastic bottle filled with water and a condiment packet makes the packet sink. Letting go of the bottle makes the packet rise.   Squeeze condiment packet (soy sauce, ketchup, etc.)Clear plastic bottle with tight-fitting lidA glass or cup of water First, you have to figure out if your condiment packet is a good Cartesian diver candidate. Fill a glass with water and drop in your packet. The best packets are ones that just barely float.  After you have found the proper packet, fill an empty, clear plastic...

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Colored Shadows - Not all shadows are black.

Colored Shadows  Not all shadows are black. When two different-colored lights shine on the same spot on a white screen, the light reflecting from that spot to your eyes is called an additive mixture because it contains the colors from both lights. We can learn about human color perception by using colored lights to make additive color mixtures.   White surface. (A white wall, white posterboard, or white paper taped to stiff cardboard works well. Do not use a beaded or metal slide projection screen.)Red, green, and blue lightbulbs or floodlamps, one of...

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