more radioactivity

• define the activity of an unstable nucleus

  activity is the rate at which a source of unstable nuclei decays
• what is the unit of radioactive activity

  becquerel
• what is the count rate

  the number of radioactive decays per second for a radioactive source
• what may be used to measure count rate

  geiger muller tube
• describe the nature of radioactive decay

  random , which nuclei decays and when is determined by chance , it is impossible to predict which nuclei will decay and when
• define the half life of a radioactive isotope

  the time it takes for the number unstable nuclei in a substance to halve , the time it takes for the count rate from a sample to fall to half of its initial level
• how do you measure and detect background radiation

  photographic film , geiger muller counter
• how is photographic film used to measure radiation

  a photographic film turns dark when it absorbs radiation , this is useful for people who work on radiation as the more radiation they are exposed to , the darker the film becomes, therefore the workers know when they have been exposed to too much radiation
• how are geiger muller tubes used to measure radiation

  when the geiger muller tubes absorb radiation it produces a pulse , which a machine uses to count the amount of radiation . the frequency of the pulse depends on how much radiation is present , a high frequency pulse would mean that the tube is absorbing a large amount of radiation
• describe how the activity of an unstable source decreases over time

  as time goes on , more and more unstable nuclei decay due to this ,the number of unstable particles decreases , this causes the overall rate of decay to decrease aswell
• give examples of uses of radioactivity

  household fire alarms , irradiating food , sterilisation of equipment , tracing and gauging thickness of materials, diagnosis and treatment of cancer