Zener Diode Questions

We know that diodes are two-terminal devices that allow current flow in only one direction. There are many types of diodes like Schottky diode, Laser diode, Photodiode, Avalanche diode, Zener diode, Light Emitting Diode, and PN junction diode. A Zener diode is designed to function in the reverse direction. It is a semiconductor device that is heavily doped in the PN junction. Zener diode is named after Clarence Melvin Zener.

Zener diodes use high voltage to generate low-power stabilised supply rails. These diodes help to generate reference voltages for circuits, mainly stabilised power supplies and are used to protect circuits from electrostatic discharge or overvoltage.

A Zener Diode is also referred to as a breakdown diode. It is a heavily doped semiconductor device mainly designed to function in the reverse direction. When the voltage across the terminals is reversed, knee voltage, known as Zener voltage, is reached. The current flows in the reverse direction when the junction breaks down. This effect is called the Zener Effect.

Types of breakdowns in Zener Diode are:

• Avalanche Breakdown
• Zener Breakdown

Avalanche breakdown occurs at a high reverse voltage in ordinary and Zener diodes. The electric field in the depletion region gets more robust when the applied reverse bias voltage reaches the Zener voltage.

The V-I characteristics of a Zener diode is classified into:

• Forward Characteristics
• Reverse Characteristics

Zener diodes are used in over-voltage protection. It is used in clipping circuits and is also used as a voltage regulator.

Read more: Zener diode as a voltage regulator

Important Zener Diode Questions with Answers

1. Operation of the Zener diode depends on the heavy doping of its _____

1. P -junction only
2. N-junction only
3. P-N junction
4. None of the options

Answer: c) P-N junction.

Explanation: In Zener diodes, heavy doping occurs in reverse bias conditions.

2. Zener diodes are developed to conduct in the reverse direction when a specified voltage is reached. What is this voltage known as?

This type of voltage is referred to as the Zener voltage. Zener voltage is sufficient for the reverse breakdown condition allowing the diode to conduct in the reverse direction.

3. The Zener diode is named after which Physicist?

It is named after the Physicist Clarence Melvin Zener.

4. State true or false: The Zener diode is used as the surge suppressor.

1. TRUE
2. FALSE

Answer: a) TRUE

Explanation: The Zener diode is used to suppress transients as it clamps potentially damaging currents away from the protected load.

5. State true or false: Diodes are used in logical gates.

1. TRUE
2. FALSE

Answer: a) TRUE

Explanation: Diodes are used in clamping circuits, clipping circuits, logic gates, and rectifiers.

6. Zener breakdown effect takes place _____

1. Above 10V
2. Below 10V
3. Above 5.5V
4. Below 5.5V

Answer: d) Below 5.5V

Explanation: Zener breakdown takes place below 5.5V.

7. The opposition offered to the flow of electricity through the Zener diode in the operating region is known as _____

1. Zener breakdown
2. Zener Resistance
3. Zener Current
4. Zener Capacitance

Answer: b) Zener Resistance

8. What is the formula to calculate the Zener resistance?

The formula gives Zener resistance:

Zener Resistance = Zener voltage/Zener current

Rz = Vz/Iz

9. Fill in the blanks: Zener current is measured in _____

1. Watts
2. Luminous intensity
3. Ampere
4. Kelvin

Answer: c) Ampere

10. State true or false: Zener diodes are used to modify or shape AC waveform clipping circuits.

1. TRUE
2. FALSE

Answer: a) TRUE

Explanation: The clipping circuit clips off one or both parts of the half cycles of an AC waveform to shape the waveform.

Practice Questions

1. Define Zener diode.
2. List the applications of the Zener diode.
3. What are the types of diodes?
4. What is Zener voltage?
5. What is the voltage tolerance of the Zener diode?