Test: Diode Circuits - 1 - Electronics and Communication Engineering (ECE) MCQ

The ripple factor measures AC fluctuations in a rectifier’s output. A full-wave rectifier has a lower ripple factor than a half-wave rectifier because it rectifies both halves of the AC input, producing an output with twice the frequency (e.g., 120 Hz for a 60 Hz input). This higher frequency results in smaller voltage fluctuations between peaks, reducing the ripple factor.
Option A: Correct, as higher frequency reduces ripple magnitude.

The assertion is true: a filter capacitor reduces ripple voltage in a full-wave rectifier by smoothing the output. The reason is also true: the capacitor charges during voltage peaks and discharges during troughs, maintaining a steadier output voltage. The reason correctly explains how the capacitor minimizes ripple.

• Option B: Correct, as both are true and R explains A.

Average value of load current,

Maximum value of load current,

Therefore, maximum AC voltage required at the input is

The ripple factor for an inductor filter is

∴  
or  

Diodes are essential components in electronic circuits, primarily used to manage voltage levels. They perform this function by behaving like a voltage source under certain conditions. Here are the key points regarding their operation:

• Clipping Voltage: Diodes can limit the maximum voltage in a circuit, preventing damage to other components.
• Forward Bias: When a diode is forward-biased, it allows current to flow, effectively acting as a voltage source.
• Reverse Bias: In reverse bias, the diode blocks current, protecting the circuit from excessive voltage.
• Applications: They are commonly used in power supply circuits and signal processing.

In summary, diodes play a crucial role in controlling voltage levels by functioning as a voltage source under specific conditions, making them indispensable in many electronic applications.

When a capacitor is connected across the output terminals of a rectifier, the output voltage:

• Essentially becomes a DC voltage.
• Undergoes minimal fluctuations, smoothing out the signal.
• Helps to store energy, providing a stable output.

This process is critical in converting the alternating current (AC) into a usable direct current (DC), which is essential for most electronic devices. The capacitor acts as a reservoir, filling in the gaps between the peaks of the rectified voltage and reducing the ripple effect.

• Assertion (A): A high value of resistor is connected across the diode in a clamper circuit for better performance.

  • This statement is true. A high-value resistor is used in a clamper circuit to limit the current and ensure proper functioning. It helps in controlling the charge and discharge rates of the capacitor, which improves the overall performance of the circuit.

• Reason (R): If this resistor is not present, the circuit will respond to a sudden decrease in the magnitude of the input pulse train, but the response to sudden increase in the amplitude will cause improper response.

  • This statement is also true. Without the resistor, the circuit may show an inappropriate response to the changes in the input signal, especially when there is a sudden increase in the amplitude. The resistor helps in stabilizing the response of the circuit to changes in the input signal by limiting the current flow and ensuring proper charge/discharge behavior.

Since both statements are true and the reason correctly explains the assertion, the correct answer is A: Both A and R are true and R is the correct explanation of A.

No filtering action is provided by bridge arrangement. Hence, reason is a false statement.