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A teacher uses a Geiger-Müller tube and a counter to measure background radiation - Edexcel - GCSE Physics - Question 5 - 2016 - Paper 1
Question 5
A teacher uses a Geiger-Müller tube and a counter to measure background radiation. The reading on the counter tube is 34 counts per minute. (i) The teacher puts a ... show full transcript
Worked Solution & Example Answer:A teacher uses a Geiger-Müller tube and a counter to measure background radiation - Edexcel - GCSE Physics - Question 5 - 2016 - Paper 1
Step 1
Calculate how much radiation detected by the Geiger-Müller tube comes from the source of beta radiation.
Answer
To find the amount of radiation from the source, we subtract the background radiation from the total reading.
Total reading = 468 counts per minute
Background reading = 34 counts per minute
Radiation from source = Total reading - Background reading
Radiation from source = 468 - 34 = 434 counts per minute.
Step 2
Estimate the reading on the counter tube.
Answer
When the thick sheet of aluminium is placed between the source of beta radiation and the Geiger-Müller tube, it will absorb most of the beta particles. Therefore, the counter will detect significantly fewer counts.
An estimated reading might be around 34 counts per minute, as this is the background radiation level, assuming the aluminium effectively blocks the beta radiation.
Step 3
Give a reason why the answer to (ii) is only an estimate.
Answer
The estimate is only approximate because the effectiveness of the aluminium sheet can vary. Some beta particles may still penetrate the sheet, and other factors such as positioning and measurement errors can also affect the reading.