This is a cool science experiment. I found it in a Family Fun magazine (Feb. 2003). I love this magazine. You may visit their site too. @ Family Fun Science fun in action!!
EXPLODING RAINBOW
One of the key ingredients to pulling off this trick is the right magic potion: dishwashing liquid. That's right, dishwashing liquid can do more than clean dinnerware; it can also turn a plate of milk into a display of swirling colors. Some brands work better than others, so be sure to test yours ahead of time. We had particularly good result with Ultra Sunlight brand.
Get Ready:
1. Fill a pie plate halfway with whole milk.
2. Pour some liquid dishwashing soap into a plastic squeeze bottle (such as an empty sports drink bottle) and label it "Magic Potion."
Showtime!
Invite everyone to gather around the pie plate and announce that you will transform the milk into a rainbow of exploding colors. Ask for a few volunteers to gently squeeze drops of red, blue, green, and yellow food coloring onto the milk (you want to end up with at least 3 drops of each hue). While saying "Abracadabra!" or something else that sounds magical, quickly drizzle the magic potion onto the surface of the milk all around the edge of the pie plate. Your audience will be amazed at what happens next. The milk will instantly turn into a kaleidoscope of colors-an entertaining display that can continue for several minutes.
Behind the Magic (sssshhhh! don't let your your secret; but then again maybe you'll want to if it is a science experiment)
What causes the colors to swirl: Milk may look like a white liquid, but it's really tiny droplets of fat (as well as proteins, carbohydrates, vitamins, and minerals) suspended in water. In this magic trick (experiment), when you first add the food coloring, it floats on top because the mild's molecules at the surface naturally stick together and support the colored drops. Adding soap, however, disturbs the surface tension by breaking the bonds between fat molecules, creating gaps that the food coloring quickly swirls into.
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