Question

According to Einstein's theory of relativity, mass can be converted into energy and vice-versa. The lightest elementary particles, taken to be the electron, has a mass equivalent to $0.51MeV$ of energy. Then we can say that

• A. The minimum amount of energy available through conversion of mass into energy is $1.02MeV$
• B. The least energy of a $\gamma -ray$ photon that can be converted into mass is $1.02MeV$
• C. Whereas the minimum energy released by conversion of mass into energy is $1.02MeV$, it is only a $\gamma -ray$ photon of energy $0.51MeV$ and above that can be converted into mass
• D. Whereas the minimum energy released by conversion of mass into energy is $0.51MeV$, it is only a $\gamma -ray$ photon of energy $1.02MeV$ and above that can be converted into mass

Answer 1

Answer: (A), (B)

The correct options are
A The minimum amount of energy available through conversion of mass into energy is $1.02MeV$
B The least energy of a $\gamma -ray$ photon that can be converted into mass is $1.02MeV$

We always have either an electron-positron pair production or an electron-positron pair annihilation, so that the total charge remains zero.

Hence, the least energy through conversion of mass into energy or through conversion of energy into mass is $1.02MeV$.