Question

With the help of neat circuit diagram explain the working of half and full wave rectifier.

Answer 1

Working of half wave rectifier:

• In a half wave rectifier, single diode is used.
• The AC from the secondary coil of the transformer AB is applied to the diode and a load resistance RL in series.
• During the positive half cycle, the diode is forward biased and current flows through the diode.
• During the negative half cycle, the diode is reverse biased and current does not flow through the diode.
• Thus, current flows during the positive half cycle only and we get a pulsating discontinuous wave.
• Efficiency of half-wave rectifier is given by

                      $n=\frac{0.406R_{L}}{r_{f}+R_{L}}$

Working of full wave rectifier:

• In a full wave rectifier, two diodes are used.
• The secondary coil of the transformer AB is center tapped between diode $D_{1}$ and $D_{2}$ as shown.
• Across the common point of n-ends and central tap C, a load resistance is connected.
• During the positive half cycle of AC diode $D_{1}$ is forward biased and $D_{2}$ is reverse biased.
• Thus, current flows throw $D_{1}$.
• During the positive half cycle of AC diode $D_{2}$ is forward biased and $D_{1}$ is reverse biased.
• Thus, current flows throw $D_{2}$.
• Hence, current flows through $R_{L}$ during the full cycle of AC and we get pulsating and continuous wave.
• Efficiency of full wave rectifier is given by

                          $n=\frac{0.812R_{L}}{r_{f}+R_{L}}$                                            

Answer 2

Half wave rectifier:

• This rectifier has PN junction diode.
• It is connected to AC power supply and a step down transformer is connected to the circuit with load resistor.
• During positive half cycle, PN junction diode undergoes forward bias. So, the current flows through the load resistor.
• During negative half cycle, PN junction diode undergoes reverse bias. Then current does not flow through the load resistor.
• Hence, the output is in one direction and pulsating in nature.
• The half wave rectifier is given in the image below.

Full wave rectifier:

• This rectifier as two crystal diode.
• It is connected to AC power supply and a centre tapped transformer is connected with load resistor.
• During both cycles, the diode conducts the current alternatively.
• Hence, current in same direction flows through the load resistor.
• The full wave rectifier is given in the image below.