Find the
(a) maximum frequency, and
(b) minimum wavelength of X-rays produced by 30 kV electrons.
(a) X-ray produced by the electron therefore has maximum photon energy (Ex) equal to energy (E) of the electron.
E = eV …(1)
Where magnitude of charge of the electron ‘e’ = 1.6 × 10-19 C
Accelerating potential is V = 30 × 103 V 3
Putting in equation (1) we get,
⇒ E = 1.6 × 10-19 C × 30 × 103 J
Also, Ex = hν
Where, Ex = maximum energy of the X-ray
And h = plank’s constant = 6.63 × 10-34 J. sec
ν = max. frequency of X-ray
⇒ vmax = Emax/h
⇒
⇒ vmax= 7.24 × 1018 Hz
Max. frequency of X-ray is 7.24 × 1018 Hz
(b) Minimum wave length (λ) of X-ray is given by the following relation.
Ex = hν = hc/λ
∴ λ = hc / Ex
c = speed of light = 3 × 108 m/s
⇒
⇒ λ = 0.041nm
Minimum wave length of X-ray is equal to 0.041nm