Rectifier is an electronic device which converts the alternating current to unidirectional current, in other words rectifier converts the alternating current voltage to direct current voltage. The process is known as rectification. Physically, rectifiers take a number of forms, including vacuum tube diodes, mercury-arc valves, copper and selenium oxide rectifiers, semiconductor diodes, silicon-controlled rectifiers and other silicon-based semiconductor switches. You can find rectifier in almost all the electronic devices because rectifier can convert the main voltage into direct current voltage in most power supply part, and every electronic device will work on the direct current voltage supply only. Rectifiers are classified according to the period of conduction. They are half wave rectifier and full wave rectifier.