The Energy released when mass is converted to energy, is given by the equation: E = mc²

– production of energy by the sun

• Energy production in the sun happens through nuclear fusion
• The light atoms such as hydrogen get fused to form a heavier atom.
• The difference in mass between the initial atoms and final product gets converted to energy according to the equation E = mc²

– particle–antiparticle interactions, eg positron–electron annihilation

• • When particles interact with their antiparticles, they get annihilated.
  • This results in the complete conversion of mass of the original particles to some form of energy.
  • Eg – electrons and positrons get annihilated to form photons.
  • e^– + e⁺ -> y + y
    • e^– : electron
    • e⁺ : positron
    • y : photon

– combustion of conventional fuel

• • combustion of conventional fuels mostly release energy due to chemical changes
  • For example, burning about 3kg of gasoline releases about 132 million joules of energy,
  • This energy if converted to mass will be 14 ng of mass.
  • Thus by losing only 14ng of mass (a negligible amount), it is able to produce 132 million joules of energy.

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