How mass can be converted into energy. give examples?

Answer 1

Mass can not be converted into energy. This is a common misconception. The example usually given is nuclear reactions. Note that this is no different from a chemical reaction, except that the energies involved (as well as the mass deficit, see below) are much greater in a nuclear reaction.

Assume that hydrogen is fused into helium, in the Sun. Some would say that "mass is converted into energy". This is not true. The mass deficit (see: "mass deficit" article in Wikipedia for more details) means that the helium has less mass than the hydrogen. However, any energy leaving the place of the reaction - for example, light leaving the Sun - also has mass! If the energy stays there, say as heat, it contributes to the total mass! Thus, total mass is conserved.

As to the energy, the light that leave the Sun has a certain energy. This energy is available before the reaction, as nuclear energy; a type of potential energy. Thus, total energy is also conserved.

Since both mass and energy are conserved, there is no mass-to-energy conversion. The same happens for other nuclear reactions, or any reaction for that matter. Both mass and energy are always conserved.

Answer 2

Mass can be converted into energy through the process of nuclear reactions, such as nuclear fission or nuclear fusion. In nuclear fission, the nucleus of an atom is split, releasing a significant amount of energy (E=mc^2). In nuclear fusion, two atomic nuclei combine to form a heavier nucleus, releasing energy in the process. This phenomenon is what powers the sun and other stars.