This is P. My first blog post. I want to post a little about our latest Saturday Science sessions before they get overtaken by the next and greatest. A couple of weeks ago we looked at "white powders" to find out why the sky is blue, why sunsets are red and how to make sherbert. A small amount of milk powder in water scatters light just like the atmosphere does. Blue light is bendiest and scatters the most in all directions as light passes across, including down to us - so the sky seems blue (on the moon, without an atmosphere, you would look up during the day and see a black sky!). As the torch light passes through more and more milky glasses, less and less blue is left until the remaining light looks quite red/orange. This is like sunset, when the sun is low in the sky and is passing through the most atmosphere of the day, on its way to us.
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| photo by RL |
The other white powders we played with were citric acid and baking soda. When mixed with water they fizz as carbon dioxide is produced. We added icing sugar and flavoured jelly crystals for some delicious lemon, lime or creaming soda sherbert.
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| photo by RL |
This week we looked at "moving hot air". RL set up a couple of great demos. The first had heat from a flame rising and causing a paper spiral to spin in the breeze. The second took a bottle from the freezer filled with ice cold air. As the air warms up out of the freezer it starts to expand and blow up a balloon. Heating the bottle expands the air even more and the balloon continues to grow.
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| spiral spinning in the heat |
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| balloon inflating as bottle warms up |
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| balloon inflating more when bottle is put under warm running water |
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