Wavelength of the proton or neutron is given as $\lambda \approx 10^{-15} \mathrm{~m}$
Rest mass-energy of an electron will be calculated as:
${{m}_{o}}{{c}^{2}}=0.511MeV$
$=0.511\times {{10}^{6}}\times 1.6\times {{10}^{-19}}$
$=0.8176\times {{10}^{-13}}J$
Planck’s constant, $\left.h=6.6 \times 10^{-34}\right\rfloor \mathrm{s}$
Speed of light, $c=3 \times 10^{8} \mathrm{~m} / \mathrm{s}$
The momentum of the proton or a neutron is given by the expression,
$p=h/\lambda $
\[=6.6\times {{10}^{-34}}/{{10}^{-15}}\] $=6.6\times {{10}^{-19}}kgm/s$
The expression for the relativistic relation for energy (E) is given as
${{E}^{2}}={{p}^{2}}{{c}^{2}}+{{m}_{0}}^{2}{{C}^{4}}$
$={{(6.6\times {{10}^{-19}}\times 3\times {{10}^{8}})}^{2}}+{{(0.8176\times {{10}^{-13}})}^{2}}$
$=392.04\times {{10}^{-22}}+0.6685\times {{10}^{-26}}$
$\approx 392.04\times {{10}^{-22}}$
$E=19.8\times {{10}^{-11}}$
$=19.8\times {{10}^{-11}}/1.6\times {{10}^{-19}}$
$=12.375\times {{10}^{8}}eV$
Order of energy of these electron beams is $12.375 \times 10^{8} \mathrm{eV}$