Select the correct advantage of a full-wave rectifier over a half-wave rectifier

Explanation:

Full-Wave Rectifier

Definition: A full-wave rectifier is an electrical device used to convert alternating current (AC) into direct current (DC). Unlike a half-wave rectifier, which only utilizes one half-cycle of the input AC signal, a full-wave rectifier makes use of both the positive and negative half-cycles of the AC input signal, thereby providing a more efficient conversion and a smoother DC output.

Working Principle:

The full-wave rectifier operates by using two diodes (in a center-tap transformer configuration) or four diodes (in a bridge rectifier configuration) to rectify both the positive and negative half-cycles of the AC input. The resulting output is a pulsating DC signal, which can be further smoothed using filters.

• Center-Tap Full-Wave Rectifier: In this configuration, a center-tap transformer is used, and two diodes are connected to each half of the secondary winding. During the positive half-cycle, one diode conducts, while during the negative half-cycle, the other diode conducts.
• Bridge Full-Wave Rectifier: In this configuration, four diodes are arranged in a bridge circuit. During each half-cycle of the AC input, two diodes conduct to allow current to flow in the same direction through the load.

Advantages of Full-Wave Rectifier:

• Utilizes both positive and negative half-cycles of the AC input, leading to higher efficiency in conversion.
• Provides a smoother DC output compared to a half-wave rectifier.
• Higher average output voltage and current.
• Reduced ripple factor, which results in less need for filtering.

Correct Option Analysis:

The correct option is:

Option 3: Higher efficiency and utilisation of both half-cycles of the AC input.

This option accurately highlights the primary advantage of a full-wave rectifier over a half-wave rectifier. By utilizing both the positive and negative half-cycles of the AC input, the full-wave rectifier achieves higher efficiency and provides a more stable and higher average DC output. This makes it more suitable for applications requiring consistent and reliable DC power.

Additional Information

To further understand the analysis, let’s evaluate the other options:

Option 1: Lower efficiency and utilisation of only one half-cycle of the AC input.

This option describes the characteristics of a half-wave rectifier, not a full-wave rectifier. A half-wave rectifier only uses one half of the AC input signal (either the positive or the negative half-cycle), leading to lower efficiency and a higher ripple factor.

Option 2: Lower cost.

While a half-wave rectifier is generally less costly due to its simpler design and fewer components (only one diode is required), this is not an inherent advantage of a full-wave rectifier. Full-wave rectifiers are relatively more expensive because they require additional components such as diodes or a center-tap transformer.

Option 4: Lower output voltage.

Full-wave rectifiers provide a higher average output voltage compared to half-wave rectifiers because they utilize both half-cycles of the AC input. This statement is incorrect as it contradicts the fundamental advantage of full-wave rectifiers.

Option 5: Lower output voltage.

This is a repetition of Option 4 and is also incorrect for the same reason. Full-wave rectifiers offer a higher output voltage and current, making them more efficient and effective for DC power supply applications.

Conclusion:

By utilizing both half-cycles of the AC input signal, the full-wave rectifier achieves higher efficiency, higher output voltage, and a smoother DC signal compared to the half-wave rectifier. These advantages make it the preferred choice in most applications where a stable and efficient DC power supply is required. The correct answer, therefore, is Option 3: "Higher efficiency and utilisation of both half-cycles of the AC input."