An electron and a positron, both essentially at rest, undergo complete annihilation. If the rest mass energy of an electron is 0.511 MeV , the total energy released in this process is:

Step-by-step solution

In pair annihilation, an electron and a positron are completely converted into energy. The mass of a positron is exactly equal to the mass of an electron. Total mass converted into energy = m_ e + m_ e = 2m_ e . Given the rest mass energy of an electron is 0.511 MeV , the total energy released is: E = 2 0.511 MeV = 1.022 MeV . The option with Joules is incorrect because the numerical value corresponds to the energy in MeV, not Joules. Answer: 1.022 MeV