4 (a) Radioactive tracers can be used when scanning a person's kidneys - Edexcel - GCSE Physics - Question 4 - 2022 - Paper 1
Question 4
4 (a) Radioactive tracers can be used when scanning a person's kidneys.
A radioactive isotope is injected into a person's blood stream.
The isotope emits radiation.
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Worked Solution & Example Answer:4 (a) Radioactive tracers can be used when scanning a person's kidneys - Edexcel - GCSE Physics - Question 4 - 2022 - Paper 1
Step 1
(a)(i) What type of radiation travels from the kidney to the scanner?
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Answer
The type of radiation that travels from the kidney to the scanner is D gamma. Gamma radiation is capable of penetrating the body and is detected by the scanner.
Step 2
(a)(ii)1. State why an isotope with a half-life of about 6 minutes is not suitable.
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An isotope with a half-life of about 6 minutes decays too quickly to provide a stable reading during the 30-minute scan.
Step 3
(a)(ii)2. State why an isotope with a half-life of about 6 days is not suitable.
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An isotope with a half-life of about 6 days would remain in the body too long, potentially causing harm or damaging other organs.
Step 4
(a)(iii) State two ways of reducing the radiation risks to the technician.
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Wear personal protective equipment (PPE) such as lead aprons or goggles to limit exposure.
Increase the distance from the radiation source, or leave the room while the patient is scanned.
Step 5
(b)(i) Explain how pushing the control rods further into the reactor slows down the nuclear reaction.
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Pushing the control rods further into the reactor absorbs more neutrons, which decreases the likelihood of further fission reactions. This effectively slows down the nuclear chain reaction.
Step 6
(b)(ii) Calculate the average speed of the slow neutrons as a percentage of the average speed of the fast neutrons.
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The average speed of the slow neutrons is given as 4.0×107 m/s, and the average speed of the fast neutrons is 3.0×107 m/s. To find the percentage:
average speed of fast neutronsaverage speed of slow neutrons×100=3.0×1074.0×107×100≈133.33%
Therefore, the average speed of the slow neutrons is approximately 133.33% of the average speed of the fast neutrons.
Step 7
(b)(iii) Describe how energy is transferred from the nuclear reaction to the next stage in the process.
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Energy generated from the nuclear reaction is transferred in the form of heat. This heat is used to produce steam from water in the reactor, which drives a turbine connected to a generator, ultimately producing electricity.
