Answer :
Solution :
Energy of photon, E = 6.7 eV
E = [tex]$6.7 \times 1.602 \times 10^{-7}$[/tex] joule
Kinetic energy, [tex]$K.E. =\frac{1}{2} mv^2 = 1.602 \times 6.7 \times 10^{-7}$[/tex]
[tex]$v^2=\frac{2 \times 1.602 \times 6.7 \times 10^{-7}}{1.6726 \times 10^{-27}}$[/tex]
[tex]$=12.834 \times 10^{-20}$[/tex]
Kinetic energy at high speeds
[tex]$(r-1)\times mc^2 = 6.7 \ eV$[/tex]
[tex]$(r-1)=\frac{6.7 \times 1.602 \times 10^{-7}}{1.6726 \times 10^{-27} \times 9 \times 10^{16}}$[/tex]
r - 1 = 7130
r = 7130 + 1
r = 7131
[tex]$\frac{1}{\sqrt{1-\frac{v^2}{C^2}}}=7131$[/tex]
[tex]$1-\frac{v^2}{C^2} = \left(\frac{1}{7131}\right)^2$[/tex]
[tex]$v^2=C^2\left[1-\left(\frac{1}{7131}\right)^2\right]$[/tex]
[tex]$v=0.99999999017C$[/tex]
Δ = 1 - 0.99999999017
= 0.00000000933
Relative mass, [tex]$m_{rel}=r.m$[/tex]
[tex]$=7131 \times 1.6728 \times 10^{-27}$[/tex]
[tex]$=1.1927 \times 10^{-23}$[/tex] kg