1.The time for half the nuclei in a radioactive sample to decay. 2.These are emitted by the source in a smoke alarm. 3.This happens when nuclear radiation travels through matter. 4.A nucleus of carbon-14 has eight of these. 5.This is one cause of background radiation. 6.During beta decay the nucleus gains one of these. 7.What must be given out by the source used to locate a blockage in an oil pipeline 2 m below ground. 8.This can be used to detect radiation. A.Ionisation D.Gamma Rays E.Geiger-Müller tube F.Half life G.Alpha particles H.Neutrons B.Cosmic Rays C.Proton

Lesson.8: Non-medical uses of Radiation Objectives Recall and describe the main non-medical uses of ionising radiation. Recall and describe the main non-medical uses of ionising radiation. Justify the choice of radiation used for a particular purpose. Justify the choice of radiation used for a particular purpose. Judge the appropriate half-life for a source used for a given purpose. Judge the appropriate half-life for a source used for a given purpose.

Tracers - finding leaks in pipes?

Smoke alarms contain a weak source of alpha radiation. Smoke Alarms The alpha particles ionize the air. If there is smoke present, it blocks some alpha particles and ionization is reduced. This means that less current is flowing through the air, which causes the alarm to sound. α α smoke particle

Radioactive dating

Radioactive dating Radioactive dating Radiocarbon dating Radiocarbon dating 14 C=Carbon :10,000,000 of the particles in all living things and the same in the atmosphere Half-life = 5730 years Dating igneous rocks Dating igneous rocks 238 U=Uranium – 238 Eventually decays to Lead Half-life = 4.5 billion years

Key facts background radiation background radiation carbon dating carbon dating half-life half-life uranium uranium radioisotopes radioisotopes cosmic rays cosmic rays smoke detector smoke detector dating rocks dating rocks ionising radiation. ionising radiation.

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Learning Objectives State that radioisotopes are used as tracers in industry. MEDICAL USES ARE COVERED LATER State that radioisotopes are used as tracers in industry. MEDICAL USES ARE COVERED LATER Recall examples of the use of tracers: Recall examples of the use of tracers: to track dispersal of waste; to track dispersal of waste; to find leaks/blockages in underground pipes; to find leaks/blockages in underground pipes; to find the route of underground pipes. to find the route of underground pipes. Describe how tracers are used in industry: Describe how tracers are used in industry: radioactive material put into pipe; radioactive material put into pipe; gamma source used so that it can penetrate to the surface; gamma source used so that it can penetrate to the surface; progress tracked with detector above ground; progress tracked with detector above ground; leak/blockage shown by reduction/no radioactivity after this point. leak/blockage shown by reduction/no radioactivity after this point. Describe that alpha sources are used in some smoke detectors. Describe that alpha sources are used in some smoke detectors. Describe how a smoke detector with an alpha source works. Describe how a smoke detector with an alpha source works. Recall that radioactivity can be used to date rocks. Recall that radioactivity can be used to date rocks. Recall that measurements from radioactive carbon can be used to find the date of old materials. Recall that measurements from radioactive carbon can be used to find the date of old materials.

Explain how the radioactive dating of rocks depends on the calculation of the uranium/lead ratio. Explain how the radioactive dating of rocks depends on the calculation of the uranium/lead ratio. Explain how measurements of the activity of radioactive carbon can lead to an approximate age for different materials: Explain how measurements of the activity of radioactive carbon can lead to an approximate age for different materials: the amount of Carbon 14 in the air has not changed for thousands of years; the amount of Carbon 14 in the air has not changed for thousands of years; when an object dies (eg wood) gaseous exchange with the air stops; when an object dies (eg wood) gaseous exchange with the air stops; as the Carbon 14 in the wood decays the activity of the sample decreases; as the Carbon 14 in the wood decays the activity of the sample decreases; the ratio of current activity from living matter to the activity of the sample leads to a reasonably accurate date. the ratio of current activity from living matter to the activity of the sample leads to a reasonably accurate date.