The activity of a source is measured in Becquerel (Bq), which is equivalent to one decay per second. The amount of radiation absorbed by cells is measured in gray (Gy), which is a joule of energy absorbed by 1 kg of the body. The activity of a radioactive source is the number of decays per second of the unstable nuclei present in the source. Geiger-Muller tubes can measure the activity of a radioactive source by converting the number of radioactive particles into a counting rate.
It is important to measure the counting rate in the absence of the radioactive source to account for background radiation. Measure the background radiation three times and find the average, then subtract this from all data recorded for radioactive sources. Safety precautions should be taken when handling the radioactive source, including using tweezers and storing it in a lead box when the experiment is complete. Detection of radioactivity, its units of measurement and radiation dose, sources of ionizing radiation - radioactive materials - are all topics covered in GCSE Physics. Radiation gamma alpha, beta &: properties of 3 types of radioactive nuclear emission & symbols, hazards of radioactive emissions: health and safety concerns and ionizing radiation physical review are also discussed.
A fundamental knowledge of atomic structure and particles is needed to understand radioactivity. If a radioactive substance physically touches an object, that object will become contaminated, since it will contain radioactive material on its surface. Radioactivity was first noticed by French physicist Henri Becquerel in 1896, when he observed that some photographic plates that had been stored near a uranium compound had been partially exposed or “tarnished”.