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Consider an X-ray tube that uses chromium (Z = 24) as its target. (a) Use the Bo

ID: 2021492 • Letter: C

Question

Consider an X-ray tube that uses chromium (Z = 24) as its target.

(a) Use the Bohr model to estimate the minimum kinetic energy electrons must have in order for K X-rays to just appear in the X-ray spectrum of the tube.
_____ keV
(b) Assuming the electrons are accelerated from rest through a voltage V, estimate the minimum voltage necessary to produce the K X-rays.
______ kV

What I did:

Started with E= -13.6eV(Z-1)2/n12

Took E and multipled by 1.6e-19. (That answer was wrong. ) I got 7.83 keV and 7.83kV both were wrong. Thank you for your help.

Explanation / Answer

atomic number of chromimum Z = 24 minimum kinetic energy (n = 1) is              Emin  =   -13.6eV(Z-1)2/n2           I Emin I = I -13.6eV(24-1)2/(1)2 I            I EminI = 7.194*103 eV            I Emin I = 7.2 keV   (approximately) ...................................................................................... charge of the electron e = 1.6*10-19 C the minimum voltage is            Vmin = 7.2 keV / 1.6*10-19 C                      = (7.2*1.6*10-19 kV) / (1.6*10-19 C)                      = 7.2 kV            I EminI = 7.194*103 eV            I Emin I = 7.2 keV   (approximately) ...................................................................................... charge of the electron e = 1.6*10-19 C the minimum voltage is            Vmin = 7.2 keV / 1.6*10-19 C                      = (7.2*1.6*10-19 kV) / (1.6*10-19 C)                      = 7.2 kV