Difference between revisions of "Count Rate"
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: For a [[Beta Particle|beta]] source the [[Count Rate|count rate]] drops to 0 beyond a few [[metre]]s because the [[beta Particle|beta particle]]s are [[Absorb (Physics)|absorbed]] by the several [[metre]]s of [[air]]. | : For a [[Beta Particle|beta]] source the [[Count Rate|count rate]] drops to 0 beyond a few [[metre]]s because the [[beta Particle|beta particle]]s are [[Absorb (Physics)|absorbed]] by the several [[metre]]s of [[air]]. | ||
: For a [[gamma-ray]] source the [[Count Rate|count rate]] drops at a rate of 1/r<sup>2<sup> where r is the distance between the source and detector. | : For a [[gamma-ray]] source the [[Count Rate|count rate]] drops at a rate of 1/r<sup>2<sup> where r is the distance between the source and detector. | ||
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| + | ===References=== | ||
| + | ====AQA==== | ||
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| + | :[https://www.amazon.co.uk/gp/product/1782946403/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782946403&linkCode=as2&tag=nrjc-21&linkId=32a0abb60dff015b15b50e9b1d7b4644 ''Count rate, page 118, GCSE Combined Science Trilogy; Physics, CGP, AQA ''] | ||
| + | :[https://www.amazon.co.uk/gp/product/1782945970/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782945970&linkCode=as2&tag=nrjc-21&linkId=a120d24dcc7cc7a58192069a3aafc1d2 ''Count rate, page 130, GCSE Physics; The Complete 9-1 Course for AQA, CGP, AQA ''] | ||
| + | :[https://www.amazon.co.uk/gp/product/1471851354/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1471851354&linkCode=as2&tag=nrjc-21&linkId=9012a0d354024419214fb3ad5ac44ba0 ''Count rate, radioactive sources, page 348, GCSE Combined Science Trilogy 1, Hodder, AQA ''] | ||
| + | :[https://www.amazon.co.uk/gp/product/019835939X/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=019835939X&linkCode=as2&tag=nrjc-21&linkId=57e96876985fc39b1a3d8a3e3dc238b6 ''Count rates, page 100, GCSE Physics; Third Edition, Oxford University Press, AQA ''] | ||
Revision as of 23:04, 3 November 2019
Key Stage 4
Meaning
Count rate is the number of particles of ionising radiation that reach a detector per second.
About Count Rate
- The SI Units of count rate are Becquerels (Bq).
- Count rate is measured using a Geiger counter.
- The count rate at the detector will be less than the radioactivity of the sample of unstable isotope because the ionising radiation spreads out in all directions equally.
- The greater the distance from the radioactive sample the lower the count rate.
- For an alpha source the count rate drops to 0 beyond 5cm because the alpha particles are absorbed by a few centimetres of air.
- For a beta source the count rate drops to 0 beyond a few metres because the beta particles are absorbed by the several metres of air.
- For a gamma-ray source the count rate drops at a rate of 1/r2 where r is the distance between the source and detector.
References
AQA
- Count rate, page 118, GCSE Combined Science Trilogy; Physics, CGP, AQA
- Count rate, page 130, GCSE Physics; The Complete 9-1 Course for AQA, CGP, AQA
- Count rate, radioactive sources, page 348, GCSE Combined Science Trilogy 1, Hodder, AQA
- Count rates, page 100, GCSE Physics; Third Edition, Oxford University Press, AQA