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Science P2 Topic 6
Edexcel GCSE additional science physics: radioactive materials
|What is background radiation?
|Radiation that is always present at a very low level, coming from space and naturally radioactive substances in the environment
|What is the main source of radiation in the UK?
|Radon gas- it is a radioactive isotope produced by the decay of uranium in a rock that diffuses into the air and builds up in houses with poor ventilation
|What affects the amount of radon gas in an area?
|Soil type, building stone used in a certain area
|What are some sources of radiation in the UK?
|Old medical equipment, food and drink, nuclear power, radon gas, cosmic rays from outer space
|What are some uses of gamma rays?
|* sterilise medical equipment * irradiate food to kill pests and allow it to last for longer * to treat cancer in radiotherapy * diagnosis of cancer using tracer solutions
|What are some uses of alpha particles?
|Americum 241 is put in household smoke alarms and ionises the air in the smoke detector producing an electric current- if smoke enters the alarm it absorbs some alpha particles which alters the current, triggering the alarm
|What are some uses of beta particles?
|It is used to check the thickness of paper- if a detector notices that there are too many or too few beta particles passing through the paper, the pressure applied on the rollers squeezing wood pulp is changed
|What is the activity of a substance?
|The number of nuclear decays per second, measured in Becquerel (Bq)
|1 Bq = ?
|1 nuclear decay per second
|What is the half life of a substance?
|The time taken for half the unstable nuclei in the substance to decay, causing the activity to decrease by half
|How is the radioactivity of a source measured?
|Using a Geiger-Muller tube- it clicks everytime ionising radiation is detected in the tube and produces a count rate (number of clicks per second/ minute)
|What are some precautions taken with radioactive materials?
|* tongs are used when handling them * they are stored in lead containers * protective clothing is worn * sources are never pointed at people * exposure time is limited
|How have scientists changed ideas about radioactivity over the years?
|19th century- people burned themselves handling radioactive sources 20th century- link was made between cancer and radioactive sources
|What are the features of high level nuclear waste?
|Sealed in glass, lasts for 50 years, very radioactive, often is spent fuel from reactors, high activity, transported in thick concrete/ lead
|What are the features of intermediate level nuclear waste?
|lasts for thousands of years, moderately radioactive, stored in concrete/steel, old high-level waste
|What are the features of low level nuclear waste?
|stored in special landfill sites, not very radioactive, remains slightly radioactive for thousands of years, often is old medical tracers
|What are the problems with the methods of disposal of radioactive waste?
|* firing into space if expensive and launch vehicle could crash back on earth * barrels that are dumped in the sea could corrode and leak * storage underground is a problem due to earthquakes