Rectification

For heating and lighting a.c. is just as good as d.c. but for some uses d.c. is needed.
Televisions, radios, battery chargers and electroplating apparatus need d.c. It is therefore useful to be able to convert a.c. into d.c. This can be done with a DIODE and the process is called RECTIFICATION.

A diode is a device that allows electricity to flow through it in one direction only

So if a.c. is applied to the diode only half of it gets through.

You can see how the positive or the negative part of the a.c. cycle can be allowed through simply by turning the diode round.


This type of output is known as HALF WAVE RECTIFICATION. Although the current is not steady it now only flows in one direction.

If a capacitor is added to the circuit as shown then the output voltage is smoothed.


In half wave rectification only half the a.c. cycle is used, the other half being blocked by the diode.

By using the circuit below, both half cycles are used.

This type of output is known as FULL WAVE RECTIFICATION and the device producing it is called a bridge rectifier (Figure 5).