An environmental safety officer is testing three salvaged industrial sensors, labeled PPP, QQQ, and RRR, to identify their radioactive emissions. The officer uses a Geiger-Müller (GM) tube and counter to measure the count rate under different shielding conditions.
The table below shows the measured count rates in counts per minute (cpm):
AbsorberNo source (background)Source PSource QSource RNone15540720410Thin sheet of paper1453816412Aluminium sheet (5 mm)161514408 \begin{array}{|l|c|c|c|c|} \hline \textbf{Absorber} & \textbf{No source (background)} & \textbf{Source } P & \textbf{Source } Q & \textbf{Source } R \\ \hline \text{None} & 15 & 540 & 720 & 410 \\ \hline \text{Thin sheet of paper} & 14 & 538 & 16 & 412 \\ \hline \text{Aluminium sheet (5 mm)} & 16 & 15 & 14 & 408 \\ \hline \end{array} AbsorberNoneThin sheet of paperAluminium sheet (5 mm)No source (background)151416Source P54053815Source Q7201614Source R410412408Based on these results:
Identify which source emits only alpha radiation\textbf{only alpha radiation}only alpha radiation and explain your choice.
Identify which source emits only beta radiation\textbf{only beta radiation}only beta radiation and explain your choice.
6 exam-style questions on AQA GCSE Physics 4.2 Atoms and nuclear radiation, covering 4.2.1 Radioactive decay and nuclear radiation, 4.2.2 Nuclear equations, 4.2.3 Half-lives and the random nature of radioactive decay, and 4.2.4 Radioactive contamination. Each one has a worked solution and a mark scheme showing where the marks go.