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

For a bridge rectifier circuit,

For ideal diode,

and hence maximum efficiency, η = 81.06%.

Ripple factor is a measure of the variation in the output voltage of a rectifier. For a full-wave rectifier without a filter, the ripple factor can be calculated using a specific formula.

The ripple factor (r) for a full-wave rectifier is given by:

• r = 0.48 for a full-wave rectifier without filtering.

This value represents the ratio of the ripple voltage to the DC output voltage, indicating how much AC voltage is present in the output. A lower ripple factor is preferable as it suggests a smoother DC output.

In summary, the key points are:

• The ripple factor for a full-wave rectifier without a filter is 0.48.
• This value indicates the level of AC voltage in the output.
• A lower ripple factor is desirable for a stable DC supply.

DC power delivered to the load is 

∴  
The ripple factor,

or  
Therefore, the AC ripple voltage across the load, 
V_AC = 1 volt

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.

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 a sudden increase in the amplitude will cause improper response.

In this context:

• A is true because using a high-value resistor helps stabilise the circuit's performance.
• R is also true as it explains that the absence of the resistor leads to inconsistent responses to changes in input voltage.
• Therefore, the reason R effectively clarifies the assertion A.

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