According to Einstein's mass energy relation, $E = $?.
(A) $mc$
(B) $m{c^2}$
(C) ${m^2}c$
(D) $m{c^{ - 2}}$

Hint: Use the Einstein concept that if the energy of any object changes by an amount E, then with the help of the speed of light, we can determine the change in the amount of object's mass. But the everyday examples of energy gain are too small to produce detectable changes in the object's mass.

Complete step by step solution:
In 1905, while developing the special theory of relativity, the famous scientist Einstein gave some information about the energy. He said that the change in the object's energy could be equivalent to the change in the object's mass if we use the speed of light to relate these two quantities, and this speed of light is known as the conversion factor. After this concept, the conversion of the object's mass into energy becomes with the help of the conversion factor (c) and vice versa. Before the generation of relativity theory, generally, it is considered a mass of the object and energy independent.

From this theory, Einstein gives the mass-energy equation related to object mass and energy. The mass energy equation is $E = m{c^2}$. Here, $E$ is the energy, is the mass and is the speed of the light.

Therefore, according to Einstein's mass energy relation $E = m{c^2}$ and option (B) is correct.

Note: Remember the mass-energy equation because from this equation, we can obtain the relation between the mass of the object and energy. This equation is very useful in the study of nuclear physics, and with the help of this equation, we can control nuclear energy.