Material

Bubble solution

10 ml Dawn dishwashing liquid, blue, "Original Scent."
100 ml water
1 ml glycerin (optional)
Mix the ingredients together, the solution will work best if you age it overnight.

Food color green or blue
White paper
Soda straws
Pie pan cheap aluminum. Other shallow pans will work.

Assembly

Make the bubble solution
Pour it into the pie pan.
add food coloring until the solution is dark.

To Do and Notice

Blow a pile of bubbles on the plate.
Press the piece of paper down onto the pile of bubbles.

Pull the paper straight away.

Notice the pattern on the paper.

Allow the paper to dry.

Notice that when two bubbles of the same size meet the wall between them is flat.
When a large bubble and a small bubble meet the wall is a part of a circle, and the circle bulges into the larger bubble.

What's Going On?

Each bubble wall is a water sandwich, the water in the sandwich contains food coloring. When the paper is pressed against the bubble pile the walls of the bubbles transfer their dye to the paper leaving a print of the pattern of bubbles.

Smaller bubbles have higher pressures inside of them than larger bubbles. (It is much harder to blow up a balloon when it is small than when it is large.) This pushes the bubble wall towards the larger bubble.

Scientific Explorations with Paul Doherty

© 2005

23 September 2005

From an activity developed by the Institute for Inquiry at the Exploratorium.