A student investigates the radiation emitted by a radioactive substance. A detector is placed near the source, and different absorbers are placed between the substance and the detector. The table below shows the counter readings, which have been corrected for background radiation:
AbsorberCounter reading (counts per minute)None240Thin paper240Few mm of aluminium95Several cm of lead8 \begin{array}{|c|c|} \hline \text{Absorber} & \text{Counter reading (counts per minute)} \\ \hline \text{None} & 240 \\ \hline \text{Thin paper} & 240 \\ \hline \text{Few mm of aluminium} & 95 \\ \hline \text{Several cm of lead} & 8 \\ \hline \end{array} AbsorberNoneThin paperFew mm of aluminiumSeveral cm of leadCounter reading (counts per minute)240240958Which types of radiation are being emitted by the substance?
α\alphaα-particles and β\betaβ-particles only
α\alphaα-particles and γ\gammaγ-rays only
β\betaβ-particles and γ\gammaγ-rays only
α\alphaα-particles, β\betaβ-particles, and γ\gammaγ-rays
134 exam-style questions on CIE IGCSE Physics 5.2.2a Alpha, beta and gamma emission. Each one has a worked solution and a mark scheme showing where the marks go.