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Science P2 Topic 6
Edexcel GCSE additional science physics: radioactive materials
| Question | Answer |
|---|---|
| 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 |
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