An) electric machine with variable torque generation having a tunable Halbach array configuration. The electric machine includes a magnet assembly for generating a magnetic field. The magnet assembly includes a plurality of fixed magnets disposed in a ring arrangement so that fixed magnets having a north pole faced toward the rotor or stator are alternated with fixed magnets having a south pole faced toward the rotor or stator, a plurality of rotatable magnets disposed within a respective slot formed between two adjacent fixed magnets, a drive assembly for turning the rotatable magnets within the slots to vary the magnetic field generated by the magnet assembly in the rotor or stator, the drive assembly configured to turn the rotatable magnets between a first position wherein the magnetic field in the rotor or stator is augmented and a second position wherein the magnetic field in the rotor or stator is cancelled.