Half-wave rectifier rectification process
The current and voltage, that the energy supplier companies delivered to our homes, offices, shops, etc., is alternating current. But the electronic devices that we have in these places use direct current. Then, the alternating current (AC) should become direct current (DC).
To make the rectification process, we use a rectifier circuit made of semiconductor diodes. An electric transformer is used to reduce the line voltage from 110/220 volts AC or other, to a lower voltage such as 12 or 15 volts AC. The rectifier circuit is placed at the output of the transformer. The voltage at the transformer secondary winding is alternating, and it has positive and negative half cycles.
Polarization of semiconductor diode in the forward direction
During the positive half cycle, the diode is forward biased, allowing current to flow through it. See the graph. If the diode is considered ideal, it behaves like a short circuit. Then all the transformer voltage secondary winding goes directly to the load resistor.
Polarization of the semiconductor diode in reverse direction
During the negative half cycle, the current supplied by the transformer secondary winding will attempt to flow in the opposite direction to the diode arrow (the diode is reverse biased). If the diode is considered ideal, it will behave as an open circuit and no current flows.
The output waveform of a 1/2 wave rectifier will be as shown in the diagram below.