Account for the release of energy in the process of nuclear fusion

  • Nuclear fusion is the process of joining two smaller nuclei to form a more stable nucleus.
  • The nucleus formed is more stable as it has a higher binding energy than the nuclei used to form it.
  • The mass defect mass defect, arising due to the higher binding energy gets released as energy, and can be calculated as delta emc2.

For example , to form a deuterium – a proton and neutron is required in the nucleus.

  • mass of proton (mp) = 1.007276u
  • mass of neutron (mn) = 1.008665u
  • mass of deuterium nucleus = 2.013553u
  • Thus mass defect = 1.007276u + 1.008665u – 2.013553u = 0.002388u
  • Note : 1 atomic mass unit, u = 1.661 x 10-27 kg.
  • This mass defect will get released as energy : E = mc2 = 0.002388 x 1.661 x 10-27 kg x (3 x 108ms-1)2

Another famous example is formation of helium nucleus from nuclei of deuterium and tritium .


Extract from Physics Stage 6 Syllabus © 2017 NSW Education Standards Authority (NESA)