NEET-XII-Physics

13: Nuclei

  • #3
    Obtain the binding energy (in MeV) of a nitrogen nucleus, given =14.00307 u
    Ans : Atomic mass of nitrogen, m = 14.00307 u

    A nucleus of nitrogen contains 7 protons and 7 neutrons.

    Hence, the mass defect of this nucleus, Δm = 7mH + 7mn - m

    Where,

    Mass of a proton, mH = 1.007825 u

    Mass of a neutron, mn= 1.008665 u

    ∴Δm = 7 × 1.007825 + 7 × 1.008665 - 14.00307

    = 7.054775 + 7.06055 - 14.00307

    = 0.11236 u

    But 1 u = 931.5 MeV/c2

    ∴Δm = 0.11236 × 931.5 MeV/c2

    Hence, the binding energy of the nucleus is given as:

    Eb = Δmc2

    Where,

    c = Speed of light

    ∴Eb = 0.11236 × 931.5

    = 104.66334 MeV

    Hence, the binding energy of a nitrogen nucleus is 104.66334 MeV.