Geiger molar tube 👀

• Radioactivity can be detected using a Geiger-Muller tube connected to a 


  counter.

  
• When alpha particles, beta particles or gamma rays enter the GM tube

  the counter clicks and the count is displayed on the screen.

  
• The number of counts per second or per minute is called the

  count rate.
• to measure the background radiation we

  • Remove all known sources of radioactivity from the room.
  • Set the counter to zero
  • Switch on and start a stop clock.
  • After 20 minutes switch off. Record the count.
  • Divide the count by 20 to calculate the count rate per minute.

  
• The background count rate is measured over a period of 20 minutes because 


  of the random nature of radioactive decay.
• Dividing by 20 enables the

  average count rate per minute to be determined.
• Background count rate is typically 18 counts per minute which does not present a


  serious health risk to humans.