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IP2.30.3 Alpha smoke alarms © Oxford University Press 2011 Alpha smoke alarms
IP2.30.3 Alpha smoke alarms © Oxford University Press 2011 Alpha particles are ideal for use in smoke alarms. Smoke alarms contain a weak source of alpha particles. They ionise the air in a chamber and a small electrical current flows between two electrodes in the chamber. When smoke enters the chamber it absorbs the alpha particles. This means that current drops and this triggers the alarm.
IP2.30.3 Alpha smoke alarms © Oxford University Press 2011 If the half life was too short then the activity of the source would fall too quickly, the current in the ionisation chamber would stop and the alarm would sound. For a smoke alarm to work properly for a number of years the activity level of the source needs to be fairly constant and therefore it needs to have a long half life. Explain why a source with a long half life is needed in a smoke detector.
IP2.30.3 Alpha smoke alarms © Oxford University Press 2011 Other types of radiation are not as ionising and so would not create the current in the detector for it to work properly. Explain why radioactive sources producing beta or gamma radiation aren’t suitable for a smoke detector.
IP Beta and paper mills © Oxford University Press 2011 Beta and paper mills.
Smoke Detectors Two types ; Use of Photoelectric Effect Use of Ionising Radiation Amercium -241 in the form of Amercium Oxide which is a decay product.
Background Radiation Background radiation is radioactivity that is always present Background radiation is caused by radioactive substances in rocks and.
Background Radiation background radiation is caused by radioactive substances in rocks and soil and by cosmic rays. Some background radiation comes from.
IP Uses of gamma © Oxford University Press 2011 Uses of gamma.
1 Alpha Emissions (How a Smoke Alarm Works). 2 Radioactive Emissions (Radiation) Penetrating Power SymbolEquivalentDescriptionType He Stopped by thick.
Nuclear power fission fusion Uranium U U fusion Nuclear power station Releases heat Heat turns _____ Into steam The steam turns the.
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