Question

Construction and working of half wave rectifier

Answer 1

Working of Half Wave Rectifier-

1. A high AC voltage is applied to the primary side of the step-down transformer. The obtained secondary low voltage is applied to the diode.
2. The diode is forward biased during the positive half cycle of the AC voltage and reverse biased during the negative half cycle.
3. The final output voltage waveform is as shown in the figure below:

For better understanding, let us simplify the half-wave circuit by replacing the secondary transformer coils with a voltage source as shown below: 

For the positive half cycle of the AC source voltage, the circuit effectively becomes as shown below in the diagram:

When the diode is forward biased, it acts as a closed switch. But, during the negative half cycle of the AC source voltage, the equivalent circuit becomes as shown in the figure below

When a diode is reverse biased, it acts as an open switch. Since no current can flow to the load, the output voltage is equal to zero.