An electrical device that allows more current to flow in one direction than the other, thus enabling alternating e.m.f.s to drive only direct current. The device most commonly used for rectification is the semiconductor diode. In half-wave rectification, achieved with one diode, a pulsating current is produced. In full-wave rectification two diodes are used, one pair conducting during the first half cycle and the other conducting during the second half. The full-wave rectified signal can be smoothed using a capacitor or an inductor. The bridge rectifier illustrated also gives full-wave rectification.