Science Experiment 4
How To Make a Rainbow
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What You Need :
Food colouring – Red, Blue, Yellow, Green
5 glasses or clear plastic cups
What to do :
1. Line up five glasses. Add 1 tablespoon (15 g) of sugar to the first glass, 2 tablespoons (30 g) of sugar to the second glass, 3 tablespoons of sugar (45 g) to the third glass, and 4 tablespoons of sugar (60 g) to the fourth glass.
2. The fifth glass remains empty.
3. Add 3 tablespoons (45 ml) of water to each of the first 4 glasses. Stir each solution. If the sugar does not dissolve in any of the four glasses, then add one more tablespoon (15 ml) of water to each of the four glasses.
4. Add 2-3 drops of red food coloring to the first glass, yellow food coloring to the second glass, green food coloring to the third glass, and blue food coloring to the fourth glass. Stir each solution.
5. Now let's make a rainbow using the different solutions. Fill the last glass about one-fourth full of the blue sugar solution.
6. Carefully layer some green sugar solution above the blue liquid. Do this by putting a spoon in the glass, just above the blue layer, and pouring the green solution slowly over the back of the spoon. If you do this right, you won't disturb the blue solution much at all. Add green solution until the glass is about half full.
7. Now layer the yellow solution above the green liquid, using the back of the spoon. Fill the glass to three-quarters full.
8. Finally, layer the red solution above the yellow liquid. Fill the glass the rest of the way.
Why this works :
In this experiment the water with the most sugar in it is the densest, so it sinks to the bottom of the fifth glass. The other water samples stay in neat layers because of the density of their water, depending on how much sugar was added to them.
Find this online at : https://www.thoughtco.com/rainbow-in-a-glass