Abstract: The electric machine of the invention operates in a synchronous manner based on the principle of reluctance variation. It comprises the following combination: a fixed portion (1) with notches (11) for receiving armature coils (12) connected in series by phase, wherein the successive windings as wound in opposite directions; a mobile portion (4) with teeth (6) facing the notches (11), wherein to a tooth of the mobile portion corresponds a number M×(2P) of notches in the fixed portion, M being an integer and P the number of phases; an excitation portion (15) with a coil or a permanent magnet for generating a continuous magnetic flow between the fixed (1) and mobile (4) portions. The invention can be used in the production of rotary or linear synchronous electric motors and in the production of alternators.