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Learning About Surface Tension
Bubbles
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Bubbles are bits of air or gas trapped inside
a liquid ball. The surface of a bubble is very thin. Bubbles are
particularly fragile when a dry object touches them. That's because soap
film tends to stick to the object, which puts a strain on the bubble.
What You Need
- 8 tablespoons of dishwashing liquid
- 1 quart water
- 1 drinking straw
- A shallow pan
What to Do
- Mix the dishwashing liquid with the
water and pour it into the pan. Give your child a straw and tell him to
blow through it as he moves it slowly across the surface of the solution.
Ask him to notice the size of the bubbles that he makes.
- Next, have your child try to make a very
big bubble that covers the surface of the pan. Have him do the following:
- Dip one end of the straw into the
solution. Then hold the straw slightly above the surface. Blow into it
very gently. He may have to try several times to make a really big
bubble.
- When he's made a bubble, have him
touch it gently with a wet finger to see what happens.
- Have him make another big bubble, then
touch it with a dry finger. What happens?
- Ask him to look closely at the bubbles
he makes. How many colors does he see? Do the colors change?
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