A student is setting up an experiment to measure the radiation emitted by a beta-emitting source using a Geiger-Müller counter. Before bringing the source into the room, the student records a low, steady rate of detections. What does this measurement represent?
The background radiation, which is ionizing radiation present in the environment from natural sources (like radon and cosmic rays) and artificial sources.
The ionizing radiation coming from the beta source while it is still in another room.
The ultraviolet radiation entering the room through the windows.
The thermal (infrared) radiation emitted by the air in the room.
484 exam-style questions on CIE IGCSE Physics 5.2 Radioactivity, covering 5.2.1 Background radiation and measuring count rate, 5.2.2a Alpha, beta and gamma emission, 5.2.2b Deflection and ionising effects of nuclear radiation, 5.2.3a Radioactive decay, 5.2.3b Effects of decay on the nucleus and decay equations, 5.2.4a Half-life, 5.2.4b Choosing isotopes for applications, and 5.2.5 Effects of ionising radiation and safety precautions. Each one has a worked solution and a mark scheme showing where the marks go.