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Figure 1 shows a sealed radioactive source used in schools and colleges - AQA - A-Level Physics - Question 1 - 2019 - Paper 3
Question 1
Figure 1 shows a sealed radioactive source used in schools and colleges. 1.1 State two safety procedures to reduce risk when using this type of source. 1.2 A seale... show full transcript
Worked Solution & Example Answer:Figure 1 shows a sealed radioactive source used in schools and colleges - AQA - A-Level Physics - Question 1 - 2019 - Paper 3
Step 1
State two safety procedures to reduce risk when using this type of source.
Answer
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Maximize distance: Use tongs or a handling tool to handle the source, staying at least 2 meters away from it to minimize exposure.
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Limit exposure time: Keep the source in use for the shortest amount of time necessary during experiments, and only when required for observation.
Step 2
Step 3
Identify which of the nuclei A to M are common to all the possible ways that 226Ra decays into 206Pb.
Answer
The nuclei that are common to all pathways from A to M that lead to the decay of 226Ra into 206Pb are those that appear in every possible route traced in Figure 2. A careful review shows nuclei D and F are present in all routes.
Step 4
State and explain procedures to eliminate systematic error in the measurements used to find Ab.
Answer
To eliminate systematic error when measuring the background count rate A_b:
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Reset procedures: Before any measurement, ensure the counter or stopwatch is reset to remove any prior readings that can skew results.
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Environmental controls: Conduct the experiment in a controlled environment, where factors like temperature or electromagnetic interference are constant.
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Repeated measurements: Measure A_b multiple times and calculate the average to account for any outliers.
Step 5
Deduce the minimum thickness of the aluminium absorber that should be used in the experiment.
Answer
Using Figure 4, the thickness required for stopping ext{β} particles can be assessed by finding where the energy of ext{β} particles drops below the threshold where ionization is negligible. A minimum thickness of 2.5 mm should effectively reduce the energy of emitted ext{β} particles from 5.5 MeV adequately.
Step 6
Deduce d using Figure 6.
Answer
From the graph plotted in Figure 6, we can observe that the slope indicates a direct relationship between d and rac{1}{ ext{A}_b^{0.5}}. By extrapolating the graph to its intercept, we can deduce that d is approximately 4.0 mm, which indicates the effective distance traveled by ext{γ} radiation considering the influences of background radiation. The suitable unit for d is millimeters (mm).
Step 7