Background radiation and radiation dose: Atomic structure: Physics: GCSE (9:1)

• Background radiation


  Radiation that is around us all of the time

  
• Sources of background radiation

  Natural sources such as rocks and cosmic rays from space and man-made sources such as the fallout from nuclear weapons testing and nuclear accidents

  
• Factors affecting exposure to background radiation

  Location and occupation among other things
• Activity


  The number of decays per second from an unstable nucleus
• Becquerel (Bq)


  The SI unit for activity
• Why activity is unsuitable to measure radiation exposure

  The activity of two sources could be the same, but one could emit alpha whereas the other emits beta (so they would each have a different effect on a person)
• When alpha radiation is more dangerous to a person than beta


  When the radioactive source is inside the body
• Why alpha radiation is more dangerous to a person than beta when inside the body

  An alpha particle is more ionising and it cannot penetrate the skin so will not be able to escape from the body
• When beta radiation is more dangerous to a person than alpha

  When the radioactive source is outside the body
• Why beta radiation is more dangerous to a person than alpha when outside the body

  A beta particle is less ionising but it can penetrate the skin so will be able to pass into the body
• Radiation dose


  A measure of the amount of damage that would be caused by the absorption of 1 joule of energy per kilogram of body mass

  
• Sievert (Sv)


  The SI unit for radiation dose
• Millisievert (mSv)


  A more commonly used unit for radiation dose, as absorption is usually less than 1 Sv
• 1 sievert (Sv) is equal to _____ millisieverts (mSv)

  1,000 millisieverts (mSv)
• Radiation dose from eating a banana

  Approx. 0.00001 mSv (if it contains radioactive potassium)
• Radiation dose from 3 months on the ISS (International Space Station)

  40 mSv
• Typical radiation dose that can lead to death

  10 Sv (10,000 mSv)