CBSE-XI-Physics
47: The Special Theory of Relativity
- #27What is the kinetic energy of an electron in electron volts with mass equal to double its rest mass?Ans : If m0 is the rest mass of an electron and c is the speed of light, then kinetic energy (E) of the electron = mc2 - m0c2. ...(1)
According to the question,
m = 2m0
E = (2m0 - m0)c2
E= m0c2 = 9.1 × 10-31 × 9 × 1016 J
`` E=\frac{9.1\times 9}{1.6}\times \frac{{10}^{-15}}{{10}^{-19}}=51.18\times {10}^{4}\,\mathrm{\,eV\,}=511\,\mathrm{\,keV\,}``
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