The rest energy of an electron is.

Options

A. `510 KeV`
B. `931 KeV`
C. `510 MeV`
D. `931 MeV`

Answer

A

Explanation

(a) Rest energy of an electron `= m_e c^2`
Here, `m_e = 9.1 xx 10^-31 kg` and `c =` velocity of light
`:.` Rest energy `= 9.1 xx 10^-31 xx (3 xx 10^8)^2` Joule
`=(9.1 xx 10^-31 xx (3 xx 10^8)^2)/(1.6 xx 10^-19) eV = 510 keV`.