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What is the total energy E of a 2.53 MeV electron? |
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Answer» Solution :KEY IDEA the total energy E is the SUM of the electron.s mass energy (or REST energy) `mc^(2)` and its kinetic energy: `E=mc^(2)+K.""`(36-57) CALCULATIONS: The adjective "2.53 MeV" in the problem statement means that the electron.s kinetic energy is 2.53 MeV. To evaluate the electron.s mass energy `mc^(2)`, we substitute the electron.s mass m from Appendix B, obtaining `Mc^(2)=(9.10xx10^(-31)kg) (299 792 458 m//s)^(2)` `=8.187 XX 10^(-14)J` Then dividing this result by `1.602xx10^(-13)J//MeV` gives us 0.511 MeV as the electron.s mass energy (confirming the value in Table 36-3). Equation 36-57 then yields `E=0.511MeV+2.53MeV=3.04MeV`. |
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