Chapter 25: Problem 50
Discuss briefly the basic difficulties in establishing the physiological effects of low-level radiation.
Chapter 25: Problem 50
Discuss briefly the basic difficulties in establishing the physiological effects of low-level radiation.
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Get started for freeWhat is the age of a piece of volcanic rock that has a mass ratio of argon- 40 to potassium- 40 of \(2.9 ?\) The half-life of potassium-40 by \(\beta\) decay is \(1.248 \times 10^{9} \mathrm{y}\) and by electron capture \(t_{1 / 2}=1.4 \times 10^{9} \mathrm{y}\).
The packing fraction of a nuclide is related to the fraction of the total mass of a nuclide that is converted to nuclear binding energy. It is defined as the fraction \((M-A) / A,\) where \(M\) is the actual nuclidic mass and \(A\) is the mass number. Use data from a handbook (such as the Handbook of Chemistry and Physics, published by the CRC Press) to determine the packing fractions of some representative nuclides. Plot a graph of packing fraction versus mass number, and compare it with Figure \(25-6 .\) Explain the relationship between the two.
A sample containing \(_{88}^{224} \mathrm{Ra},\) which decays by \(\alpha\) -particle emission, disintegrates at the following rate, expressed as disintegrations per minute or counts per minute \((\mathrm{cpm}): t=0,1000 \mathrm{cpm} ; t=1 \mathrm{h}\) \(992 \mathrm{cpm} ; t=10 \mathrm{h}, 924 \mathrm{cpm} ; t=100 \mathrm{h}, 452 \mathrm{cpm}\) \(t=250 \mathrm{h}, 138 \mathrm{cpm} .\) What is the half-life of this nuclide?
One method of dating rocks is based on their \(^{87} \mathrm{Sr} /^{87} \mathrm{Rb}\) ratio. \(^{87} \mathrm{Rb}\) is a \(\beta^{-}\) emitter with a half- life of \(5 \times 10^{11}\) years. A certain rock has a mass ratio \(^{87} \mathrm{Sr} /^{87} \mathrm{Rb}\) of \(0.004 / 1.00 .\) What is the age of the rock?
Explain why the rem is more satisfactory than the rad as a unit for measuring radiation dosage.
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