Materials Required:
l Scissors
l Sponge
l Mayonnaise jar with lid
l Glue
l Tin snips
l Carbon paper
l Rubbing alcohol
l Dry ice
l Slide projector
The help of one of your parents
Procedure:
- Cut a piece of sponge so that if fits into the bottom of a mayonnaise jar. Glue the sponge in place.
- Ask one of your parents to cut out a 1-inch piece of metal from the side of the jar’s lid with a pair of tin snips. Do not handle the edges because they will be sharp.
- Next, cut a piece of carbon paper into a circle that will fit into the metal lid. Place the paper in the lid carbon side up.
- Pour some rubbing alcohol into the jar and let the sponge soak up as much of this liquid as it can. Then turn the jar upside down, let it drain completely, and screw on the lid. Ask your parent to set the device, still upside down, on a small piece of dry ice.
- Shine a projector light into the cutaway section of the lid. In about 10 minutes, you will see tiny trails skirting across the black background of the carbon.
This Is What Happens:
You have just constructed a diffusion cloud chamber. This instrument makes the paths of nuclear particles visible. Nuclear particles may come from outer space, the earth’s natural radioactivity, or from man-made sources such as power plants. As the alcohol in the sponge vapourizes, it slowly sinks to the lid where it is cooled by the dry ice underneath. The motion of nuclear particles through this cool vapour creates trails of fog, which you are able to see because of the bright light.
