Wednesday, March 29, 2017

Teapot Swirls

Here's something to notice when you're making tea on a cold day. If you pour cold and hot water together, you might notice swirls of light in the water. Not because the water is colored (it's not), but because the hot and cold water have different densities, and thus bend light in slightly different ways. Mix them, and you can see the fluid swirling as light bends at the boundaries between the hot and cold.



Monday, March 13, 2017

St. Patrick's Day Chromatography

Why is the color green such a fun candy color? Because you can separate it with chromatography.

Here’s how to see the dyes that make up the green color on an M&M or jelly bean.
  1. Cut a rectangular strip of coffee filter paper.
    Dab a drop of water onto a plate, then put the candy on the water. This will dissolve a little bit of the color.
    Dab the color to make a spot of color near the bottom of the strip.
  2. Place the strip in a small glass with about a 1/2 inch of water. The bottom of the paper should be in the water, with the spot above the water.
  3. After a few minutes, look for new colors. Can you see any yellow near the bottom? Or blue on top?



And if you have leprechauns and rainbows on the brain, try the experiment with a brown or black piece of candy. You’ll see an array of colors.


Now, that’s a St. Patrick’s day rainbow!

Monday, March 6, 2017

Egg Drop

An object in motion tends to stay in motion, while an object at rest tends to stay at rest.

Such as an egg resting on a cardboard tube, even when the tube is batted away. Until it drops.