University of Virginia Physics Department Protection from Radiation A Physical Science Activity

Student Activity

Materials

• Geiger counter
• Radioactive sources such as:
  • Gas lantern mantle
  • Fiesta ware pottery (orange glaze)
  • Luminescent clock face
  • Smoke detector
  • Commercially available radioactive source from science supplier
• Shielding materials such as:
  • Paper
  • Aluminum foil
  • Brick
  • Jar of water
  • Piece of wood
  • Sheet of lead

Procedure

1. Set up the Geiger counter according to the unit's instructions, be sure it is calibrated.
2. Test each source item by placing the item 5 cm away from the Geiger counter probe. Keep the probe steady for 15 seconds, and find the average reading on the meter. The needle will shift around some, so choose a value in the middle of its oscillations. Record your findings in the data table.
3. Select the three source items with the highest readings. One at a time, place the source far enough away from the Geiger counter probe so that you will be able to fit the thickest piece of shielding in between the probe and the source. Test each of the shielding materials by placing them between the source and the counter. Follow the same procedure as in step 2 when taking the reading. Remember to keep the probe at the same distance for each measurement. Record your findings in the data table along with the thickness of each type of shielding that you use..
4. Answer the questions on the worksheet after you have recorded your findings.

Data Sheet

To print out the Data Sheet only, click here.

Data Table Source Without Shielding Paper Aluminum Brick Jar of Water Wood Lead Gas lantern mantel               Fiesta ware pottery               Luminescent clock face               Smoke detector                 Questions  1. Which item had the highest reading?   2. Which item had the lowest reading?   3. Do you think the density of the shield was important? Why?   4. Do you think the thickness of the shield was important? Why?