What is the difference between transformer and rectifier?

4)What is the difference between a transformer and a rectifier? Which are found in a PC Power supply?

• Answer:

  A transformer is basically used to step up or step down the mains power supply (in terms of voltage). In contrast, the rectifier is used to convert an alternating current (AC) or voltage to direct current (DC) or voltage. Wikipedia provides the following definitions which might be helpful to you. A transformer is an electrical device that transfers energy from one electrical circuit to another by magnetic coupling, where relative motion between the parts is not required to transfer energy between the circuits. It is often used to convert between high and low voltages, for impedance transformation, and to provide electrical isolation between circuits.Almost all rectifiers comprise a number of diodes in a specific arrangement for more efficiently converting AC to DC than is possible with just a single diode. Rectification is commonly performed by semiconductor diodes. Both will be found in a PC power supply since the mains is AC and the PC requires 12v DC supply which will be done by the rectifier. The stepping down of the voltage will be done by the transfoirmer coil.