A full-wave rectifier uses two junction diodes ($D_1$ and $D_2$) and a center-tapped transformer. The center tap is usually taken as the zero-voltage reference point.

• Circuit Description: The secondary winding of the transformer is connected to the two diodes. The load resistance $R_L$ is connected between the center tap and the common junction of the two diodes.

(Note: Examiner expects a neat circuit diagram showing the center-tapped transformer, two diodes, and the load resistor $R_L$.)

• Positive Half Cycle: During the first half of the input AC cycle, the potential at the upper end of the secondary coil is positive with respect to the center tap. Diode $D_1$ becomes forward-biased and conducts, while $D_2$ is reverse-biased and does not conduct. Current flows through $R_L$ in a specific direction.
• Negative Half Cycle: During the second half of the input AC cycle, the potential at the lower end of the secondary coil becomes positive with respect to the center tap. Diode $D_2$ becomes forward-biased and conducts, while $D_1$ is reverse-biased. Current flows through $R_L$ in the same direction as in the first half.

Since the current through the load resistance $R_L$ flows in the same direction for both halves of the input cycle, the output across $R_L$ is a unidirectional pulsating DC voltage.

Input/Output Waveform Representation:

• Input: A continuous sinusoidal wave oscillating between $+V_m$ and $-V_m$.
• Output: A series of positive half-cycles (humps) with no negative components, representing the rectified DC output.

Conclusion: The full-wave rectifier effectively converts both halves of the AC input into a unidirectional output, resulting in a higher average DC output voltage compared to a half-wave rectifier.