ionising radiation

• What are the three types of ionising radiation?

  Alpha, beta, and gamma
• What are the characteristics of alpha particles?

  • Composed of two protons and two neutrons
  • Emitted from the nucleus
  • Strongly ionising
  • Travel a few cm in air
  • Stopped by a sheet of paper
• What is the composition of an alpha particle?

  Two protons and two neutrons
• How far can alpha particles travel in air?

  A few cm
• What stops alpha particles?

  A sheet of paper
• Why are alpha particles strongly ionising?

  Because of their size
• What are the applications of alpha radiation in the home?

  • Used in smoke detectors
  • Ionises air particles to create a current
  • Smoke binds to ions, stopping the current
  • Alarm sounds when current stops
• What is a beta particle?

  A fast-moving electron released by the nucleus
• What is the charge of a beta particle?

  -1
• How do beta particles ionise?

  They are moderately ionising
• How far can beta particles penetrate materials?

  Moderately far
• What absorbs beta particles?

  A sheet of aluminum around 3 mm thick
• What happens to a neutron when a beta particle is emitted?

  A neutron turns into a proton
• What are the uses of beta radiation?

  • Testing the thickness of metal sheets
  • Particles are not immediately absorbed
  • Variations in thickness affect radiation passing through
• What are gamma rays?

  Waves of electromagnetic radiation
• How do gamma rays penetrate materials?

  They penetrate far without being stopped
• Why are gamma rays weakly ionising?

  They tend to pass through atoms
• What can absorb gamma rays?

  Thick sheets of lead or metres of concrete
• How do the ionising properties of alpha, beta, and gamma radiation compare?

  Alpha is strongly ionising, beta moderately, gamma weakly