Two radioactive sources, X and Y, are spilled on a laboratory floor. At the moment they are spilled, both sources have the same activity. Source X has a half-life of 2 minutes. Source Y has a half-life of 30 years.
Define the term half-life.
A week later, a scientist checks the floor. Explain which source is more hazardous a week after the spill.
A student says: 'A source with a short half-life is always less dangerous than a source with a long half-life.' Suggest why source X could be more dangerous than source Y in the first few minutes after the spill, if each source contains the same number of radioactive nuclei.
48 exam-style questions on OCR GCSE Physics 6.2 Uses and hazards, covering 6.2.1 Contamination and irradiation, 6.2.2 Half-life and radiation hazards, 6.2.3 Medical uses of nuclear radiation, 6.2.4 Nuclear fission and chain reactions, and 6.2.5 Nuclear fusion. Each one has a worked solution and a mark scheme showing where the marks go.