Half Life

• Half life


  The time it takes for the amount of radioactive nuclei to decay by half
• Radiation is measured in Bq/Becquerels
• Fire alarms 


  Alpha ionises the air, allowing current to flow. Alpha is stopped by smoke so it will disrupt the current and cause the alarm to sound.
• Industrial Tracers


  A small amount of a radioactive substance is put into a system to sense a leakage/blockage
• Fire alarms contain Alpha
• Measuring thickness


  When radiation passes through an object some of it is absorbed.

  Thicker material = more radiation absorbed
• Carbon Dating


  Comparing the two different types of carbons to estimate the age of an object.

  C14 is radioactive so decays over time, whereas C12 remains the same.
• Sterelising Equipment


  Gamma destroys bacteria and micro-organisms
• Medical Tracers


  Person swallows a small amount of radioactive material, as it decays radiation can be detected showing blood clots and problems with kidneys.

  Gamma radiation half life is around a day which is enough time to observe issues without causing damage
• Internal Radiotherapy 


  Radioactive material (beta or alpha) is injected into a tumor to destroy the cancerous cells.

  Half life should be short enough to kill the cancer
• Modelling half life using cubes

  1. Count cubes to ensure you have 50
  2. Shake the tub and throw cubes into a tray
  3. Record the number of cubes landed with the shaded side up and remove them
  4. Repeat with the remaining cubes
  5. Repeat steps 2 and 3 (9 times)
  6. Draw a graph ( Y axis = totals, X axis = number of throws)
  7. Find half life