The electrical diode is a two-terminal circuit component that allows the flow of electrical current in one direction. It comprises a PN junction forming the boundary between two semiconductor materials (n and p-type). The p-type material has holes as the majority carriers, while the n-type material has electrons as the majority carriers. The junction between these two materials creates a depletion region in which there are no free charges. When a potential difference source is connected to the diode in the forward direction, the depletion region narrows, allowing current to flow through. In the reverse direction, the depletion region widens, preventing current from flowing. Diodes are widely used in electronic circuits to regulate current flow and rectification properties. They can also be used as voltage regulators, oscillators, and signal modulators. One of the most common diodes is the rectifier diode, which converts AC voltage to DC voltage. Another type is the light-emitting diode (LED) that generates light when electric current runs through it. LEDs are employed in different applications, such as lighting, displays, and indicators.
Electrical Engineering Online shares Objective Electrical MCQ Questions on Diode.
The primary role of a diode in an electrical circuit
The primary role of a diode in an electrical circuit
- To amplify signals
- To generate power
- To rectify current
- To regulate voltage
Correct Answer: 3. To rectify current
Explanation:Diodes are primarily used to allow current flow in one direction while blocking it in the opposite direction, thus enabling the conversion of alternating current (AC) to direct current (DC).
A forward-biased diode
A forward-biased diode:
- Allows current flow in the forward direction
- Blocks current flow in the forward direction
- Allows current flow in both directions
- Blocks current flow in both directions
Correct Answer: 1. Allows current flow in the forward direction
Explanation: When a diode is forward-biased, it allows current to flow in the forward direction by reducing the barrier potential.
In reverse bias, a diode
In reverse bias, a diode:
- Blocks current flow
- Increases the voltage across it
- Conducts current easily
- Generates power
Correct Answer: 1. Blocks current flow
Explanation: When a diode is reverse-biased, it blocks current flow by increasing the barrier potential.
The voltage drop across a forward-biased silicon diode is approximately
The voltage drop across a forward-biased silicon diode is approximately:
- 0.3 V
- 0.7 V
- 1.2 V
- 1.8 V
Correct Answer: 2. 0.7 V
Explanation: The voltage drop across a forward-biased silicon diode is typically around 0.7 volts.
A Zener diode is primarily used for
A Zener diode is primarily used for:
- Rectification
- Voltage regulation
- Amplification
- Switching
Correct Answer: 2. Voltage regulation
Explanation: Zener diodes are specifically designed to regulate voltage in a circuit by maintaining a constant voltage across them, even when the applied voltage varies.
When a diode is operating in a reverse breakdown region
When a diode is operating in a reverse breakdown region:
- It behaves as an open circuit
- It behaves as a closed circuit
- It behaves as an amplifier
- It behaves as a resistor
Correct Answer: 2. It behaves as a closed circuit
Explanation: A diode in the reverse breakdown region allows current to flow in the reverse direction, behaving as a closed circuit.
The P-N junction of a diode is formed by
The P-N junction of a diode is formed by:
- Two N-type materials
- Two P-type materials
- One N-type and one P-type material
- One N-type and two P-type materials
Correct Answer: 3. One N-type and one P-type material
Explanation: The P-N junction of a diode is formed by combining one N-type semiconductor material with one P-type semiconductor material.
The reverse breakdown of a diode is caused by the following
The reverse breakdown of a diode is caused by the following:
- Applying a reverse voltage above a certain threshold
- Applying a forward voltage above a certain threshold
- Temperature changes
- Current flow in the forward direction
Correct Answer: 1. Applying a reverse voltage above a certain threshold
Explanation: Reverse breakdown occurs when a reverse voltage exceeds a certain threshold, causing a sudden increase in current flow.
The process of combining an N-type semiconductor and a P-type semiconductor to form a diode is called
The process of combining an N-type semiconductor and a P-type semiconductor to form a diode is called:
- Reverse biasing
- Forward biasing
- Doping
- Junction formation
Correct Answer: 4. Junction formation
Explanation: The process of combining an N-type and a P-type semiconductor to create a P-N junction is called junction formation.
What is the purpose of the depletion region in a diode
What is the purpose of the depletion region in a diode
- To enhance current flow
- To provide resistance
- To store charge
- To create a barrier to the current flow
Correct Answer: 4. To create a barrier to the current flow
Explanation: The depletion region, which is the region around the P-N junction of a diode, creates a barrier to current flow without an external bias voltage.
A Schottky diode is known for
A Schottky diode is known for:
- Its ability to handle high voltages
- Its low forward voltage drop
- Its sizeable reverse breakdown voltage
- Its high-frequency response
Correct Answer: 2. Its low forward voltage drop
Explanation: Schottky diodes are characterized by their low forward voltage drop, which makes them suitable for applications that require fast switching and low power loss.
What happens when a diode is forward biased
What happens when a diode is forward biased
- Current flows easily
- Current is blocked
- The diode heats
- The diode becomes damaged
Correct Answer: 1. Current flows easily
Explanation: When a diode is forward-biased, it allows current to flow easily in the forward direction.
The type of diode that emits light when forward-biased
The type of diode that emits light when forward-biased?
- Zener diode
- Photodiode
- Light-emitting diode (LED)
- Schottky diode
Correct Answer: 3. Light-emitting diode (LED)
Explanation: LEDs are designed to emit light when forward-biased, making them commonly used in lighting applications.
The reverse recovery time of a diode refers to
The reverse recovery time of a diode refers to:
- The time it takes for the diode to turn off
- The time it takes for the diode to turn on
- The time it takes for the diode to reach breakdown voltage
- The time it takes for the diode to recover from reverse bias
Correct Answer: 1. The time it takes for the diode to turn off
Explanation: The reverse recovery time of a diode is the time it takes for the diode to switch off after being forward-biased.
The purpose of a flyback diode is to
The purpose of a flyback diode is to
- Prevent reverse voltage spikes
- Regulate voltage in a flyback converter
- Protect against voltage surges
- Eliminate electromagnetic interference
Correct Answer: 1. To prevent reverse voltage spikes
Explanation: A flyback diode, also known as a freewheeling diode, is used in circuits with inductive loads to prevent reverse voltage spikes when the load current is interrupted
The breakdown voltage of a Zener diode
The breakdown voltage of a Zener diode:
- Is fixed and constant
- Varies with temperature
- Decreases with increasing current
- Increases with increasing current
Correct Answer: 1. Is fixed and constant
Explanation: The breakdown voltage of a Zener diode is designed to be fixed and constant, providing precise voltage regulation.
The varactor diode is primarily used for
The varactor diode is primarily used for:
1. Voltage regulation
2. Rectification
3. Frequency modulation
4. Current amplification
Correct Answer: 3. Frequency modulation
Explanation: Varactor diodes, also known as variable voltage capacitors, are primarily used for frequency modulation in electronic circuits.