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A radioactive isotope has a half-life of 6 hours - OCR Gateway - GCSE Physics - Question 23 - 2019 - Paper 1
Question 23
A radioactive isotope has a half-life of 6 hours. 50g of the isotope are put in a container. What mass of the isotope is left after 6 hours? (b) This is a graph s... show full transcript
Worked Solution & Example Answer:A radioactive isotope has a half-life of 6 hours - OCR Gateway - GCSE Physics - Question 23 - 2019 - Paper 1
Step 1
What mass of the isotope is left after 6 hours?
Answer
To find the mass of the radioactive isotope remaining after one half-life, we can use the formula:
ext{Mass remaining} = rac{ ext{Initial mass}}{2^{n}}where is the number of half-lives that have passed. In this case, the initial mass is 50g and one half-life (6 hours) has elapsed. Therefore, .
Calculating the mass remaining:
ext{Mass remaining} = rac{50 ext{g}}{2^{1}} = rac{50 ext{g}}{2} = 25 ext{g}Thus, the mass of the isotope left after 6 hours is 25g.
Step 2
Do you agree with the views of scientist 1 and scientist 2?
Answer
To analyze the views of both scientists, we need to compare their statements with the graph provided.
Scientist 1 claims that isotope A is more hazardous than B due to its higher activity. To confirm this, we can look at the radiation emitted and the corresponding activity levels. If the graph shows a higher count rate for isotope A compared to B, then Scientist 1's statement is supported.
Scientist 2 argues that isotope B is more hazardous because it has a longer half-life. A longer half-life often indicates lower activity; however, it may also mean it emits radiation for a longer time period. To evaluate this, we need to consider both the activity and the potential exposure time.
In summary, if the graph indicates that isotope A indeed has a higher activity, I would agree with Scientist 1. Conversely, if evidence shows that isotope B has significant long-term radiation exposure potential, I might lean towards agreement with Scientist 2.
Step 3
Describe how Scientist 1 does the experiment and explain how they can work out the type of radiation emitted.
Answer
Scientist 1 can use the following method to identify the type of radiation emitted from isotope A:
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Setup the Apparatus: Place the radiation detector behind varying thicknesses of materials, such as cardboard, thick lead, and aluminum.
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Measure Radiation: Starting with no material, record the count rate from the detector. Then, sequentially add each material and note the count rates after each addition.
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Analyze Results:
- If the count rate decreases significantly with cardboard but remains high with lead, it suggests that the radiation is alpha particles, as alpha radiation is stopped by paper or cardboard but not by lead.
- If the count rate decreases with aluminum and cardboard but remains with lead, it indicates beta radiation, as beta can penetrate cardboard and aluminum but does not pass through thicker lead.
- If the count rate is not significantly blocked by any material, it indicates gamma radiation, which requires thick lead to reduce its intensity.
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Conclusion: Summarize the findings based on the variations observed in count rate corresponding to each shield material. The type of radiation can therefore be inferred based on how effectively it is absorbed by the materials.