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2 (a) Describe how a teacher should use a Geiger-Müller (GM) tube to compare the count-rates from two different radioactive rocks - Edexcel - GCSE Physics: Combined Science - Question 2 - 2018 - Paper 1
Question 2
2 (a) Describe how a teacher should use a Geiger-Müller (GM) tube to compare the count-rates from two different radioactive rocks. (b) A hospital uses a radioactive... show full transcript
Worked Solution & Example Answer:2 (a) Describe how a teacher should use a Geiger-Müller (GM) tube to compare the count-rates from two different radioactive rocks - Edexcel - GCSE Physics: Combined Science - Question 2 - 2018 - Paper 1
Step 1
Describe how a teacher should use a Geiger-Müller (GM) tube to compare the count-rates from two different radioactive rocks.
Answer
To compare count-rates from two different radioactive rocks using a Geiger-Müller (GM) tube, follow these steps:
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Prepare the Setup: Place the Geiger-Müller tube in a suitable position where it can detect radiation from the rocks. Ensure that the tube is not in direct contact with either rock to avoid interference.
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Measure Count Rate: Measure the count rate separately for both rocks. This can be done by using the GM tube to record the number of counts over a specific time period, ensuring consistent timing for both rocks.
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Control Conditions: Keep the distance from the source-detector the same for both readings to ensure accurate comparison.
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Background Measurement: Take into account the background radiation by measuring the background count to subtract this from the counts recorded for each rock.
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Record Readings: After completing the measurements, record the readings from both rocks and calculate the average count rates, if multiple measurements were taken.
Step 2
Complete the graph on Figure 4, as accurately as possible, to show how the count-rate from this isotope will change from the time of the first measurement.
Answer
- At the first measurement (time = 0 hours), the count rate is at 80 cpm.
- After the first half-life of 6 hours, the count rate will decrease to 40 cpm.
- After the second half-life (12 hours), the count rate will decrease to 20 cpm.
- After the third half-life (18 hours), the count rate will decrease to 10 cpm.
The graph should show a smooth curve starting at 80 cpm and decreasing points at 40 cpm, 20 cpm, and 10 cpm, with a decreasing gradient connecting these points.
Step 3