Question: Differentiate between half-wave and full-wave rectification. With the help of a circuit diagram, explain the working of a full-wave rectifier.

Step 1 (Conceptual Differentiation): [1 Mark]

• Half-Wave Rectifier: Rectifies only one half of the input AC cycle. It uses a single diode. The efficiency is low ($\approx 40.6\%$).
• Full-Wave Rectifier: Rectifies both halves of the input AC cycle. It typically uses two diodes and a center-tapped transformer. The efficiency is higher ($\approx 81.2\%$).

Step 2 (Circuit Diagram Description): [1 Mark]

A full-wave rectifier consists of a center-tapped transformer, two junction diodes ($D_1$ and $D_2$), and a load resistor $R_L$. The center tap is usually grounded, and the two ends of the secondary coil are connected to the anodes of $D_1$ and $D_2$.

Step 3 (Working Mechanism): [1 Mark]

• During the positive half-cycle: The end of the secondary coil connected to $D_1$ becomes positive, making $D_1$ forward-biased. Current flows through $R_L$. Simultaneously, $D_2$ is reverse-biased and conducts no current.
• During the negative half-cycle: The end connected to $D_2$ becomes positive, making $D_2$ forward-biased. Current flows through $R_L$ in the same direction as before. $D_1$ is now reverse-biased.
• Conclusion: Since current flows through $R_L$ in the same direction for both half-cycles, the output is a unidirectional pulsating DC voltage.

💡 EL10 Concept Insight: Think of a full-wave rectifier like a two-way pump that always pushes water in the same direction, no matter which way the handle is turned; it captures both the "up" and "down" strokes of the AC signal to keep the current flowing steadily in one direction.