The intrinsic properties of electrons are fundamental for the progress of science. The relationship between electron mass and its electric charge and spin is poorly explored. Thus, through the Relativistic Quantum Theory, we have investigated the equivalence between mc² and qc², where m and q are, respectively, the mass and the electric charge of the electron. We demonstrated that ∆E = mc² ≡ Aqc², where A (A = 5.68562964 × 10−12KgC−1) is the proportionality constant obtained through the ratio of the spin g-factor and the gyromagnetic ratio for a free electron. The alignment of the spin magnetic dipole moment with the magnetic field ceases the electron precession movement. Therefore, the kinetic energy, associated with the precession, is dissipated with an intensity equal to mc². This result is promising for the production of clean and sustainable energy, besides new technological applications.