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Electrons of mass m with de-Broglie wavelength fall on the target in an X-ray tube. The cutoff wavelength ( 0) of the emitted X-ray is
(1) 0 = 2mc 2h
Momentum of electron: p = h kinetic energy K = p22m = h22m 2
Cutoff wavelength: the whole K goes into one photon:
hc 0 = h22m 2
0 = 2mc 2h
Answer: (1)
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