5 Radioactivity and Nuclear EnergyChapter 1 Radiation and Radioactivity1Radiation and RadioactivityPractice 1.1 (p.9)1D2C3A4B5(a)Heavy metal(b)T(c)P: negative, Q: positive6X-ray passes through the hand and reaches thefilm. Therefore, the film is darkened. As X-raypenetrates flesh more than bone, the part of flesh on the film is darker.7(a)By c= fλ,frequency =c=98105.1103= 2 1017Hz(b)Any one of the following:Medical imagingLuggage and container inspection(Or other reasonable answers)Practice 1.2 (p.28)1B2C3B4C5A6Any two of the following:Store and transport all sources in a suitable lead container. Lock them away when not in use.Always handle the sources with forceps or a special lifting tool, not with hands. Take great care not to drop the sources.Keep the sources at arm’s length, and point it away from the human body, especially the eyes.Carefully plan the experiments to minimize the time that the source is used.7Only radiation can be shielded.8(a)Yes. The type of radiation can be known by measuring the range of the radiation.(b)Yes. Distinctive tracks are formed in the diffusion cloud chamber by different types of radiation.9and radiation can be absorbed by a 5-mm thick aluminium sheet. Put the radioactive source in front of a G-M counter and record the count rate. Then put a 5-mm thick aluminium sheet between the source and the counter. If the count rate of the source does not vary significantly, that means the source does not emit and radiation.(Or other reasonable answers)10(a)(i)No. The count rate is about the same when a piece of paper is inserted.This shows that the source does notemit radiation.(ii)Yes. The count rate drops significantly when the 5-mm aluminium is inserted.This shows that the source emits radiation.New Senior Secondary Physics at Work (Second Edition)1Oxford University Press 2016
5 Radioactivity and Nuclear EnergyChapter 1 Radiation and Radioactivity (iii)No. The count rate is about the same when the 5-mm aluminium is replaced with 25-mm lead.This shows that the source does notemit radiation.(b)88 min–111Since radiation cannot penetrate the paper wrapping the film, we cannot deduce whether they are exposed to radiation.
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