alleryMass-energy equivalence: rest energy of electron (m_e = 9.11 × 10⁻³¹ kg):
A511 keV (= 0.511 MeV)
B13.6 eV
C1 GeV
D1 MeV
Answer & Solution
Correct answer: A. 511 keV (= 0.511 MeV)
E_rest = m_e c² = 9.11 × 10⁻³¹ × (3 × 10⁸)² = 8.2 × 10⁻¹⁴ J = 511 keV. Famous value.
**Mass of positron and proton:** 511 keV and 938.3 MeV.
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