Electronics

what are the components of a DC POWER SUPPLY?
please give your answers properly soon because this is a question of my assignment.

A transformer must be one for it has to step down the AC voltage, rectifier is another like a diode to make it one polarity instead of having the polarity switch every second, there maybe capacitors and resistors every a variable resistor if you want to make the current go lower and higher. This is not a complete picture but a very shrewd guess using my old knowledge of electronics, you need to do a bit more research but I hope this helps you fill in a lot of the blanks. Try this url too about rectification and pay close attenion to bridge rectifiers http://en.wikipedia.org/wiki/Rectifier

Try an encyclopedia or your textbook. There are different kinds of DC power supplies so anything we tell you here might be different from your textbook anyway. And then you can get mad at everyone online who hurt your homework grade. Except really you should read the chapter.