Introduction

Droplets of food coloring break into smaller droplets over and over again when dripped into water.

Material

A clear container of water, at least 1 liter.

Food coloring, try different colors.

Optional, vegetable oil.

To Do and Notice

Drip a single drop of food coloring into the container of water.

Notice that the drop falls, spreads, and then breaks up into smaller drops.

These droplets then fall and break up into smaller droplets.

The process continues making a beautiful pattern.

What's Going On

The food coloring is usually mixed into glycerin and is denser than water.

The droplets fall under gravity.

As they fall they break up into smaller droplets.

(The droplets mix with water and so have no surface tension as they would if they fell through air.)

This happens over and over again, it is a fractal process.

Different colors of food coloring have different densities and so break up in different ways.

Etc.

Put a layer of oil on top of the water.

Drip the food coloring through the oil.

Notice how beautiful colored spheres of food coloring are formed as it drops through the oil. Food coloring in glycerin and water does not mix with oil and so does have a surface tension which shapes it into a ball.

Notice how the balls sometimes stop when they meet the water and then suddenly break through. The balls have a coating of oil. This coating of oil thins allowing the ball of food coloring to touch the water and rupture.

Scientific Explorations with Paul Doherty

© 2005

23 September 2005

Etc from Patrik Waldenstrom.