Question

Find the frequency of 1 mev photon. Given wavelength of a 1 kev photon is 1.24×10−9m

Answer 1

Energy E = hν = hc/λ = 1 keV  -----------(1)

Wavelength λ = 1.24 x 10-9 m  -----------(2)

From (1) and (2), we get

hc = λ x 1 keV = 1.24 x 10-9 m x 1 keV = 1.24 x 10-9 m. 103 eV = 1.24 x 10-6 eV.m

If E = hc/λ = 1 MeV

 1/λ = E/hc = 1 x 106 eV/(1.24 x 10-6 eV.m)

                 = 0.81 x 1012/m

Frequency ν = c/λ = (3 x 108 m/s) x 0.81 x 1012/m

                               = 2.43x 1020/s

                                = 2.43 x 1020 Hz.