Chapter 32: Q14CQ (page 1182)
Why does the fusion of light nuclei into heavier nuclei release energy?
Short Answer
The reason for energy release is that heavier nuclei have more binding energy.
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Chapter 32: Q14CQ (page 1182)
Why does the fusion of light nuclei into heavier nuclei release energy?
The reason for energy release is that heavier nuclei have more binding energy.
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Verify by listing the number of nucleons, total charge, and electron family number before and after the cycle that these quantities are conserved in the overall proton-proton cycle in \(2{e^ - } + {4^1}H{ \to ^4}He + 2{\nu _e} + 6\gamma \).
Fallout from nuclear weapons tests in the atmosphere is mainly \({}^{{\rm{90}}}{\rm{Sr}}\) and \({}^{137}Cs\) , which have \(28.6\) - and \(32.2y\) half-lives, respectively. Atmospheric tests were terminated in most countries in 1963, although China only did so in 1980. It has been found that environmental activities of these two isotopes are decreasing faster than their half-lives. Why might this be?
The annual radiation dose from \(^{14}{\rm{C}}\)in our bodies is \(0.01\,{\rm{mSv}}/{\rm{y}}\). Each \(^{14}{\rm{C}}\) decay emits a \({\beta ^ - }\) averaging \(0.0750\,{\rm{MeV}}\). Taking the fraction of \(^{14}{\rm{C}}\)to be \(1.3 \times {10^{ - 12}}\;{\rm{N}}\)of normal \(^{12}{\rm{C}}\), and assuming the body is \(13\% \) carbon, estimate the fraction of the decay energy absorbed. (The rest escapes, exposing those close to you.)
The energy produced by the fusion of a \(1.00 - kg\) mixture of deuterium and tritium was found in Example Calculating Energy and Power from Fusion. Approximately how many kilograms would be required to supply the annual energy use in the United States?
Energy input is required to fuse medium-mass nuclei, such as iron or cobalt, into more massive nuclei. Explain why.
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