Question

The short wavelength limit of the X–rays produced, through the ‘complete conversion’ of the energy of a beam of electrons, accelerated through a potential, V, is 0.4125 . Taking h = 6.6×10–34 J–*. The value of V, and the deBroglie wavelength, associated with a beam of electrons, accelerated through a potential of V volts, are (nearly) equal, respectively, to

(1) 30 kV and 0.7

(2) 30 kV and 0.07

(3) 3 kV and 0.007 nm

(4) 3 kV and 0.7 nm

Answer 1

Correct option : (2) 30 kV and 0.07

Explanation :

The energy of the accelerated beam of electrons = eV. When this energy is completely converted into X–rays of wavelength 0.4125 , we have