A radioactive tracer is injected into a patient so that a doctor can look at the patient's kidneys. Why is an isotope with a half-life of a few hours used?
Its activity is low during the scan, so the radiation can leave the body
Its activity stays constant for several days, so the scan can be repeated
Its activity falls quickly after the scan, so the patient's dose is reduced
Its activity rises during the scan, so a clearer image of the kidneys forms
40 exam-style questions on AQA GCSE Physics 4.3 Hazards and uses of radioactive emissions and of background radiation, covering 4.3.1 Background radiation, 4.3.2 Different half-lives of radioactive isotopes, and 4.3.3 Uses of nuclear radiation. Each one has a worked solution and a mark scheme showing where the marks go.