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When a small radioactive source is placed in a cloud chamber, straight tracks about 4 cm long are observed - AQA - A-Level Physics - Question 18 - 2019 - Paper 2
Question 18
When a small radioactive source is placed in a cloud chamber, straight tracks about 4 cm long are observed. The same source is placed 10 cm from a Geiger tube and a ... show full transcript
Worked Solution & Example Answer:When a small radioactive source is placed in a cloud chamber, straight tracks about 4 cm long are observed - AQA - A-Level Physics - Question 18 - 2019 - Paper 2
Step 1
Identify the radiation emitted
Answer
The question indicates that straight tracks about 4 cm long are observed in a cloud chamber. This suggests the presence of charged particles, likely alpha (α) and beta (β) radiation.
The Geiger tube detecting radiation 10 cm away indicates that the radiation can travel through the air, meaning it is less likely to be alpha radiation since alpha particles have very low penetration power.
The significant decrease in count rate when a 5 mm thick sheet of aluminium is placed indicates that the radiation is indeed beta (β), as beta particles can be absorbed by materials like aluminum, while gamma (γ) radiation would still pass through.
Thus, the source emits both alpha and beta radiation, making option D: α and β the correct answer.