Charge invariance refers to the fixed value of the electric charge of a particle regardless of its motion. Like mass, total spin and magnetic moment, particle's charge quantum number remains unchanged between two reference frames in relative motion. For example, an electron has a specific charge e, total spin ℏ ℏ 2 , and invariant mass m e. Accelerate that electron, and the charge, spin and mass assigned to it in all physical laws in the frame at rest and the moving frame remain the same – e, ℏ ℏ 2 , m e. In contrast, the particle's total relativistic energy or de Broglie wavelength change values between the reference frames.