Name: Common Base Configuration
Uploaded: 2019-07-19
Duration: 14 min 41 s
Description: Let's connect the battery to all three terminals of a transistor and understand the relation between the emitter current, base current and collector current.

Question

What is Zener diode? Explain with a circuit diagram, how a Zener diode regulates the voltage across a load resistance

Accepted Answer

A Zener diode is a heavily doped silicon semiconductor device that permits current to flow in either a forward or reverse direction. The diode consists of a special, heavily doped p-n junction, designed to conduct in the reverse direction when a certain specified voltage is reached called Zener voltage. It is a diode in which at a critical reverse voltage a large reverse current can flow.

Zener diodes are widely used as voltage references and as shunt regulators to regulate the voltage across small circuits. When connected in parallel with a variable voltage source so that it is reverse biased, a Zener diode conducts when the voltage reaches the diode's reverse breakdown voltage.

A Zener diode is connected as shown. The output voltage is taken across a load resistance $R_{L}$ . When the input d.c across the diode increases beyond the breakdown voltage, the current through the circuit rises sharply, causing a sufficient increase in voltage drop across load resistance $R_{L}$ . As a result of it, the voltage across the Zener diode remains constant and the output voltage lowers back to normal.

When the input d.c. voltage across Zener diode decreases, the current through the circuit goes down sharply causing a sufficient decrease in the voltage across dropping resistance, hence the output voltage across the resistor is raised to normal. Thus, the output voltage remains constant.

Embibe Experts Solutions for Chapter: Electronic Devices, Exercise 1: West Bengal Board-2019

Embibe Experts Physics Solutions for Exercise - Embibe Experts Solutions for Chapter: Electronic Devices, Exercise 1: West Bengal Board-2019

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