Physics - Modern Physics Question with Solution | TestHub

Antiparticles of stable particles (such as the position and the antiproton) are them selves stable. However, when a particle and its antiparticle meet, the annihilation reaction clan occur, the particle and antiparticle both vanish and instead two or more photons can be produced. Conservation of energy and momentum require that, neglecting the kinetic energies of the particles, when two photons are emitted each must have an energy equal to the rest mass energy of the particles. Thus when electron-positron pair annihilate each other, the energy released is equal to rest mass of electron and positron. $$\begin{array}{c}{e}^{-}+e^{+}\to {\gamma }_1+{\gamma }_2\\ \left[E_{{\gamma }_1}=E_{{\gamma }_2}=0.511\mathrm{MeV}=0.8\times 10^{-13}\mathrm{J}\right]\end{array}$$ The total energy released $=1.6\times 10^{-13}\mathrm{J}$.