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Wave Optics

Question
CBSEENPH12038651

The nucleus Ne1023 decays by β- emission. Write down the β-decay equation and determine the maximum kinetic energy of the electrons emitted from the following data:
m(Ne1023) = 22.994466 um(Na1123) = 22.989770 u

Solution

The β-decay of Ne1023 may be represented as:

            Ne1023  Na1123 - e-10 + v¯ + Q 

Ignoring the rest mass of antineutrino v¯ and electron , we get 

Mass defect,                  
                   m = m(Ne1023) - m (Na1123)         = 22.994466 - 22.989770          = 0.004696 u          

  Q = 0.004696×931 MeV = 4.372 MeV. 

This energy of 4.3792 MeV, is shared by e- and v¯ pair because, Na1123 is very massive.

The maximum K.E. of e- = 4.372 MeV, when energy carried by v¯ is zero.

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