question_answer

The wavelength of most energetic X-rays emitted when a metal target is bombarded by 40KeV  electrons, is approximately (\[h=6.62\times {{10}^{-34}}\] J-sec; 1 eV = \[1.6\times {{10}^{-19}}\]J; c = \[3\times {{10}^{8}}\,m/s)\] [MNR 1991; MP PMT 1999; UPSEAT 2000; Pb. PET 2004]

A)            300 Å                                       

B)            10 Å

C)            4 Å

D)            0.31 Å