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Question
Iron emits Kα X-ray of energy 6.4 keV. Calculate the times taken by an iron Kα photon to cross through a distance of 3 km.
(Use Planck constant h = 4.14 × 10-15 eVs, speed of light c = 3 × 108 m/s.)
Solution
Given:
Energy of the X-ray, E = 6.4 keV
Distance travelled by the photon, d = 3 km = 3 `xx ` 103 m
Time taken by the photon to cross the distance of 3 km is given by
`t = "Distance"/"Speed" = (3 xx 10^3)/(3 xx 10^8)`
`t = 10^-5 "s" = 10 xx 10^-6 "s"`
`t = 10 mus`
Both the Kα photon and X-ray will take the same time, that is, 10 μs , to cross the distance of 3 km.
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