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Difference between Zener Diode and Normal Rectifier Diode

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A diode is a two-terminal electronic device that conducts electricity in one direction. It has high resistance on one end and low resistance on the other end. Diodes are used to protect circuits by restricting the voltage and are also used to change AC to DC. Diodes have two terminals that are known as anode and cathode.

What is Zener Diode?

Zener diode can provide a stable reference voltage. These diodes can be operated in reverse biased and break down at a certain voltage. These diodes are mostly used in power supplies to provide a reference voltage.

In the forward biased condition, it allows current and in the reverse bias, it blocks the current. After this voltage has suppresses the breakdown point (in reverse bias), the diode falls in the Zener region, where it conducts without getting damaged. Current in this region is called avalanche current.

What is a Normal Rectifier Diode?

A rectifier is a device that is used to convert an AC voltage to DC voltage. It consists of a diode, a step-down transformer and a filter. It is a simple p- n junction diode, which is normally used for rectification in a half-bridge and a full-bridge rectifier.

Difference between Zener Diode and Normal Rectifier Diode:

 

Zener diode

Normal Rectifier Diode

1. Zener diode can provide a stable reference voltage. These diodes can be operated in reverse biased and break down at a certain voltage. These diodes are mostly used in power supplies to provide a reference voltage. A rectifier is a device that is used to convert an AC voltage to DC voltage. It consists of a diode, a step-down transformer and a filter. It is a simple p- n junction diode, which is normally used for rectification in a half-bridge and a full-bridge rectifier.
2. It is a p-n junction diode with a heavily doped than compared to the normal diode It is a simple p-n junction diode
3. Zener diodes are never used for rectification purposes. These are used for the rectification of half-bridge and full-bridge rectifiers.
4. It is used as a voltage regulator in electronic devices. These are used in computers, batteries etc
5. It conducts current in both directions and can recover, unlike rectifier diodes. These are only used for allowing current/ voltages to flow only in one direction.
6. The current-carrying capability of the Zener diode is low. The current-carrying capability of the rectifier diode is high.
7. Zener diode has low inverse peak voltage. It has a high inverse peak voltage.
8. It is also called a Breakdown Diode It is also called a Silicon Diode.

Sample Questions 

Question 1: Why is the Zener diode not used as a rectifier?

Answer: 

We donot use a zener diode in a rectifier circuit because in a rectifier circuit a high maximum peak inverse voltage is required. Zener diode has low inverse peak voltage unlike other normal diodes. This is the reason zener diode is not used in rectification purpose.

Question 2: A 6V Zener diode exhibits a normal voltage at a current of 24mA. At this current the incremental resistance is 5ohms. Find Vzo of the zener diode?

Answer:

Given, Vz = 6v

Current I = 24mA

Resistance R = 5 ohms 

Vz = Vzo + IR 

6 = Vzo + (24*10-3*5) 

6= Vzo + 120*10-3

Vzo = 6 – 12/100 

Vzo = 5.88V

Therefore, the Vzo of the zener diode is 5.88V

Question 3: Explain how the Zener diode maintains a constant voltage across the load?

Answer: 

Zener diodes can behave like a dc battery in ‘ON’ state. It the zener diodes are shunted across the load with resistance RL and the voltage across the zener diodes is more than the zener voltage Vz, when the zener diode is in ON state, any changes in voltage across the zener diode is due to the changes in either the supply voltage or load resistance is not able to change the output voltage. Therefore, zener diode maintains voltage constant across the load.

Question 4: What are the applications of the Zener diode?

Answer:  

Zener diodes are used in voltage regulators. At the point when the load voltage approaches breakdown voltage, the resistor which are in the series restricts the current through the diode when there is an excess measure of voltage while the diode is conducting.

Question 5: What are the applications of rectifier diode?

Answer: 

  • These are used in power supplies to convert A.C to D.C and the process is called as rectification.
  • These are used in all electronic equipments inside the power supplies.
  • They are also used in the circuits where large current passes through the diodes.
  • These are also used in transformers.
  • It is used in AM radio as a detector, as the output of it consists of an audio signal.
  • These are used in firing circuits, pulse generating circuits, voltage multiplier and also used for modulation.

Question 6: What is the working principle of rectifier diode?

Answer: 

Rectifier diodes are allows electrical current flow only in one direction and is mainly used  for power supply operation in electronic devices. These diodes can handle higher current flow than the normal diodes.


Last Updated : 12 Jan, 2023
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