A radioactive material is placed near a detector.
The detector shows a count rate of 45 000 counts/min45\,000\text{ counts/min}45000 counts/min.
When a sheet of paper is put between the material and the counter, the reading decreases to 38 000 counts/min38\,000\text{ counts/min}38000 counts/min.
When an aluminium sheet is put between the material and the counter, the reading decreases to 15 000 counts/min15\,000\text{ counts/min}15000 counts/min.
When a thick lead block is put between the material and the counter, the reading remains at 15 000 counts/min15\,000\text{ counts/min}15000 counts/min.
What is being emitted by the radioactive material?
α\alphaα, β\betaβ and γ\gammaγ-radiation
α\alphaα and β\betaβ-radiation only
α\alphaα and γ\gammaγ-radiation only
β\betaβ and γ\gammaγ-radiation only
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.