Topic 6

• What does half life mean?

  The time it takes for the mass or the radiation to half
• What is the unit of activity?

  Bq
• Explain how a smoke alarm works.

  Use Alpha with a long half life so it doesn't need replacing. Smoke blocks alpha.
• Explain how radioactivity can be used as a tracer in the human body and as a tracer in a pipe? What type of radiation is used and why?

  Gamma used with a short half life ...
• What type of radiation do we use to measure the thickness of aluminium and why? What type of half life is needed?

  Beta, because aluminium stops beta if it is too thick - long half life so it doesn't need replacing
• Why don’t we use alpha radiation in the body for tracers?

  Most ionising and cannot pass through skin.