Question

What should be the rest energy of an electron ?

• A. $510KeV$
• B. $931KeV$
• C. $510MeV$
• D. $931MeV$

Answer 1

Answer: (A)

Rest energy of an electron is due to its mass.
From Einstein mass energy equation, $E=m{c}^2$ .
Here $m=9.1\times 10^{-31}kg$ and $c=3\times 10^{8}m/s$
So, $E=9.1\times {\left(10\right)}^{-31}\times {\left(3\times 10^8\right)}^{2}J$
or $E=\frac{9.1\times 10^{-31}\times {\left(3\times 10^8\right)}^2}{1.6\times 10^{-19}}eV=510KeV$