Americium-241, 95241Am^{241}_{95}\text{Am}95241Am, is an α\alphaα-emitter used in domestic smoke detectors. Inside the detector, the radiation ionizes the air between two electrodes, allowing a current to flow. If smoke enters, the smoke particles easily absorb the α\alphaα-particles, dropping the current and sounding the alarm.
Which properties of α\alphaα-particles, compared to other nuclear emissions, enable this use of americium-241?
high ionising effect, high penetration
high ionising effect, low penetration
low ionising effect, high penetration
low ionising effect, low penetration
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.