Northwest Arkansas Democrat-Gazette
• Rainbow Science
RAINBOW science By Karen Rice Official Kids Mag Rainbows are gorgeous and sometimes you can see one in the sky after it rains! But do you know you can also make rainbows at home? Here are some awesome, magical rainbow science experiments, just for you! WHAT IS A RAINBOW? We think of the sun as a yellow ball, sunlight is actually made up of many colors. …the colors of the rainbow! After it rains we sometimes see a rainbow in the sky. Why? It is usually when the sun is behind us and it is shining through millions of tiny water droplets in the air. These little water droplets bend the light. The light gets split up into its 7 different colors: red, orange, yellow, green, blue, indigo and violet. And we see a rainbow! Red tends to bend the least, so it appears on the top of the rainbow, while violet bends the most and ends up on the bottom – with all the other colors in between. But you don’t need always need raindrops to make a rainbow. Here are some ways to make rainbows of your own INSIDE! HOW TO MAKE A RAINBOW You can bend light yourself to make your own rainbows! When the light bends through a something like water or a prism or crystal, the light bends and you can see the spectrum of colors that make up a rainbow. Here are some simple ways to make rainbows. MIRROR AND A BOWL OF WATER You will need: Small mirror Large bowl or dish White paper Fill a large bowl or dish halfway with water and prop up a mirror inside it so that part of the mirror is under the water and part is out. Place your rainbow maker near a sunny window with direct light coming in so that it hits the mirror (early morning or early evening light works best). Play around with holding a large white piece of paper above the bowl to “catch” the rainbow. You might have to move a bit until you find it. Play around with moving the paper closer to the mirror and then farther away to see how your rainbow changes! SAFETY NOTE: Just like you should never look directly into the sun, be sure that you do not look directly into the reflection from the mirror. It can damage your eyes. GLASSES OF WATER AND A FLASHLIGHT You will need: Clear drinking glasses of different sizes and shapes Flashlight White sheet When light goes through a glass of water – it also splits into a rainbow. Fill several different sizes and shapes of clear drinking glasses with water in varying amounts. For example, fill a large ice tea glass halfway, a small shot glass all the way to the top and a juice glass about 3/4 full. The important part is to gather as many different sizes and shapes of glasses as you can. Place the glasses on a flat surface such as a coffee table. Push the glasses slightly over the edge of the table, so that slightly less than half of the glass bottom is hanging over the edge of the table. Place the large white bedsheet on the floor in front of the glass. This will serve as your “screen” for being able to see the colored spectrum clearly as the light shines through each glass and creates a rainbow. Switch on the flashlight and shine the light from behind the glasses, toward the sheet. You may need more than one flashlight for this step, especially if you are using a number of different glasses. You may have to experiment with the angle of the light in order to create a clear rainbow spectrum on the white sheet, perhaps even standing on a chair or stepladder to create the right effect. Create ripples in the water with your fingers to make your rainbows appear to sparkle and shimmer. CD AND FLASHLIGHT Make awesome rainbows using a small flashlight and a CD. Shine the light from your flashlight onto the surface of the CD to make a bold beautiful rainbow each time. Or, just hold a CD up to some sunlight to see a rainbow on the CD. The reason a rainbow appears is because there are tiny ridges in the surface of the CD that are reflecting the light in different directions. CRYSTAL AND NATURAL LIGHT Use a crystal or a prism and natural sunlight to make rainbows everywhere. If you’re lucky enough to have a crystal chandelier at home, or a hanging crystal decoration, or even a prism, you can make rainbows everywhere! Put the crystal or prism near a sunny window and experiment with moving the prism or in different ways and exploring how to change the size and shape of the rainbows. OTHER OUTDOOR RAINBOWS Here are some other ways to see and create rainbows: Misting a hose on a sunny day with the sun behind you Looking for rainbows in bubbles Looking for rainbows in oil slicks in puddles or lakes.
MORE RAINBOW SCIENCE: MILKY RAINBOWS You’ll need: • Whole milk (enough to cover bottom of cookie sheet or shallow flat bottom saucer) • a few different colors of food colouring • dish detergent • a cookie tray or flat bottom dish • popsicle sticks or q-tips or small paint brush To start, pour some milk into a cookie tray or dish (just enough to cover the bottom) and add a few drops of food coloring throughout. Dip the sticks, q-tips or paint brush in the soap and then into the milk. Watch as the milk “runs” away from the detergent in mini-explosions/rainbows! THE SCIENCE: This movement happens as the fat from the milk reacts with the soap. The food coloring makes it possible for us to see this chemical reaction. Why did the dish soap make the milk swirl? When the dish soap liquid is added to the milk, it reduces the milk’s surface tension. The food coloring and water in the milk gets pulled away from the fat particles. This results in a colorful swirling motion.