A student uses a Geiger-Müller tube connected to a ratemeter to measure the background count rate in a laboratory over a 5-minute period. Which option correctly describes the readings they obtain and the explanation for this behavior?
The counts remain completely constant because background radiation is stable.
The counts fluctuate with no predictable pattern because radioactive decay is a random process.
The counts steadily decrease to zero because the detector loses charge over time.
The counts follow a repeating wave-like pattern because background radiation is affected by daily temperature changes.
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.