Date: November 15, 1999

Grade Level(s): 8, 9

Subject(s):

• Science/Physics

Description: Students experience radioactive decay and calculate the kinetic energy of alpha particles.

Goals: Students utilize an inquiry-based, concrete method to explore radioactivity and kinetic energy; the activity illustrates relationships between scientific concepts.

Objectives: Students quantitatively measure the kinetic energy of an alpha particle and relate the energy in the cloud chamber to a nuclear reactor.

Materials:

• cloud chamber
• radioactive source
• dry ice
• rubbing alcohol
• flashlight
• cookie tray
• oven mit
• stopwatch
• tennis ball
• calculator
• distance/energy expenditure chart of an alpha particle

Procedure:

1. Ask students what they know about Geiger counters.
2. Careful with dry ice.
3. Groups of 4-5
4. Assign tasks: 1 recorder, 1 flashlight holder, 2-3 observers
5. Assign gatherers: 1 gets dry ice (with mit), 1 gets cloud chamber plus source, 1 gets rubbing alcohol and flashlight, 1 gets a copy of the energy/distance chart
6. swab the felt in the chambers with alcohol.
7. place the chamber on the dry ice.
8. wait for condensation to form (about 5 minutes).
9. insert source
10. observe particles (number and distance).
11. compile data in a list.
12. instruct the form of the alpha particle; illustrate the low level of energy with F=ma.
12. convert distance to energy for each particle
13. add up energy levels
14. compare that with light bulb
15. relate to nuclear power production (radioactivity as a source of heat).