======Measuring Radioactivity with a Geiger Counter======


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**Alternative titles:** Radioactivity in Common Objects
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====Summary====                   
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====Procedure====  
  - Turn on the Geiger counter with the audio enabled so that each detection event produces audible clicks.
  - Place the detector near a known radioactive sample such as:
    - Coleman lantern mantle (thorium source)
    - Smoke detector (americium source)
    - Fiesta ware dinner plate (uranium oxide glaze)
  - Record the count rate for each source.
  - Place a piece of lead between the detector and the source to show how shielding reduces the count rate.
  - Extend the demo to everyday items:
    - Place the detector near a banana (contains potassium-40).
    - Place it near common household items (e.g., granite, salt substitute with potassium chloride).
  - Compare the background count rate to the different items to highlight relative levels of natural radioactivity.



====Links==== 
Radioactivity Demo: Assorted sources - Physics Demos: 
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====Variations====
  * Measure the count rate at different distances from the source to illustrate the inverse-square law of radiation intensity.
  * Compare shielding effectiveness of paper, aluminum foil, and lead to show how different radiations penetrate materials.
  * Use multiple everyday food items (bananas, Brazil nuts, potatoes) to compare natural potassium-40 levels.
  * Measure background radiation in different locations around the room or building.



====Safety Precautions====
  * Handle all radioactive materials carefully, especially unsealed items like lantern mantles.
  * Wash hands thoroughly after handling sources.
  * Do not attempt to open or modify smoke detectors or radioactive samples.
  * Store radioactive objects in a secure location when not in use.
  * Use lead shielding cautiously—avoid unnecessary handling.




====Questions to Consider====
  * Why do some everyday items like bananas emit detectable radiation? (They contain potassium-40, a naturally occurring isotope.)
  * Why does a smoke detector contain americium? (Americium-241 emits alpha particles that ionize air, allowing the detector to sense smoke.)
  * Why does lead shielding reduce the radiation count? (Its high density absorbs or blocks radiation, especially gamma rays.)
  * Why is it important to measure background radiation before testing samples? (It establishes a baseline for comparison.)