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Relative Physics

If U235 captues a neutron to form U236 in its ground state, the energy released is B(U236) - B(U235).

(a) Prove this statement.
(b) Use the binding-energy formula to estimate the energy released, and compare with the observed value of 6.5 MeV.

(Note: We have assumed here that U236 is formed in its ground state, and the 6.5 MeV is carried away, by a photon, for example. An important alternatice is that U236 can be formed in an excited state, 6.5 MeV above the ground state. This excitation energy can lead to oscillations that cause the nucleus to fission.)

Solution Preview

a) Rest mass energy = np*mp + nn*mn - B
where, np = no. of protons = Z = 92 (for U)
nn = no. of neutrons = A - Z
= 235 - 92 = 143 (for U235)
= 236 - 92 = 144 (for U236)
mp = mass of a proton = 1.00783 u
mn = mass of a neutron = 1.00867 u
B = binding ...

Solution Summary

Solution uses rest mass energy = np*mp + nn*mn - B to prove this statement and includes calculations for (a) and (b).

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