Physics Key stage 4 Atomic Structure Uses of

Physics - Key stage 4 - Atomic Structure Uses of Radiation (Physics only) Mr van Hoek

Smoke Detector 2 Alpha Detector

Modelled Answer Americium-241 decays via alpha decay and has a half-life of 432 years. Explain why Americium is an appropriate isotope to use in a smoke detector. ● In a smoke detector, a constant level of radiation is needed, otherwise the detector would need to be replaced regularly. Americium-241 has a long half-life which makes it ideal. It should last several decades before the activity drops. ● Alpha particles have a low penetrating power so will be easily blocked by smoke and able to detect when smoke is present. ● Alpha particles are highly ionising so the are able to create an electrical charge in the detector which can be picked up when there is no smoke. 3

Beta Source Detector 4

Scaffolded task Cobalt-60 is within paper production to measure thickness. Cobalt-60 decays via beta decay and has a half-life of 5. 3 years. Explain why Cobalt-60 is useful in paper production. The penetrating power of beta radiation is __________. This means that the paper will ________ absorb the beta. When the paper is thicker ____ radiation will reach the _______ and the computer will adjust the rollers to make the paper ______. The ionising power of beta is _______ because beta has a charge of _______. This means that it will be reliably detected in the detector. The half-life of Cobalt-60 means that the radiation source will need to be replaced every few ______ to keep the level of radiation constant. 5

Credit : pixabay, Radaon_tanvir Medical diagnostics Detector 6

Which isotope and why? 7 Isotope Half-life Radiation emitted Carbon-14 5, 730 years Beta Carbon-11 20. 3 minutes Beta Iodine-131 8. 04 days Beta Sodium-24 15 hours Beta Technetium-99 m 6. 02 hours Beta Sodium 24 14. 9 hours Gamma Barium 137 2. 6 minutes Gamma

Independent task Barium-137 is within hospitals as a radioactive isotope for medical diagnosis. The half-life of Barium-137 is 2. 6 minutes and it decays via gamma decay. Explain why Barium-137 is useful in medical diagnosis. 3 paragraphs ● Half-life ● Penetrating Power ● Ionising Power 8

Food production Gamma Source 9

Credit : pixabay, Radaon_tanvir Radiotherapy Source 10

Finding cracks in underground pipes Detector Crack that liquid leaks from Pipe with water / oil etc 11

Exam Question - Irradiation and Contamination Greg is in hospital for some medical tests using a radioactive tracer. He tells his friends about his tests. Here are three things he says. Statement 1 : “They gave me a radioactive drink which was giving out gamma radiation. ” Statement 2 : “Then a radiographer used a detector to measure the radiation on the outside of my body. ” Statement 3 : “Now that I have taken some radioactive drink I will always be highly radioactive. ” Which of his statements could be correct and which must be incorrect? Explain why. OCR, June 2016, B 722/01 [3 marks] 12

Exam Question - Precautions Polly and Oliver were talking about the factory that is near their home. Polly said that the factory produces dangerous radioactive waste. Oliver said that if the waste was put into thick aluminium cans it could be stored safely. Is Oliver correct? _ _ _ _ _ _ Explain your answer. [2 marks] OCR, June 2016, B 712/02 Science Modules B 2, C 2, P 2 13

Exam Question - Paper thickness monitoring Katy investigates how the count rate from radioactive sources changes when different thicknesses of card are placed between a source and a radiation detector. Look at the diagram. Look at the table of results. Radioactive source Radiation detected in cpm for different thicknesses of card 0. 05 mm 0. 10 mm 0. 15 mm 0. 20 mm 0. 25 mm A 2008 1995 2012 2010 1992 B 3 4 2 3 4 C 2001 1252 808 612 452 OCR, June 2015, B 712/01 Science Modules B 2, C 2, P 2 14

Exam Question - Paper thickness monitoring Radioactive source Radiation detected in cpm for different thicknesses of card 0. 05 mm 0. 10 mm 0. 15 mm 0. 20 mm 0. 25 mm A 2008 1995 2012 2010 1992 B 3 4 2 3 4 C 2001 1252 808 612 452 It shows the count rate at the radiation detector in counts per minute (cpm) for three radioactive sources, A, B and C. A card manufacturer uses radioactive source C to monitor the thickness of card. Explain why. OCR, Specimen, J 250/06 paper 6 [2 marks] 15