Example zener diode circuit analysis blank ku ittc. The zener diode working principles and its various applications. Ncert exemplar solutions, cbse 12th physics, chapter 14. By using an led and a zener diode we can create a circuit which gives turns on the led when a voltage exceeds a certain value. Zener diodes are simple and useful devices for building voltage regulator circuits, but are times when you may have to improvise in the absence of the proper zener diode. But when it is reverse biased above a certain voltage known as zener breakdown voltage or zener voltage or avalanche point or zener knee voltage the voltage remains constant for a wide range of current. Zener diodes are generally employed in multimeters to protect the meter movement against the damage from the accidental overloads. This was a bad thing before the whole avalanche breakdown, large current.
The current through pn junction flow only from p toward n and not from n toward p. Zener designed a pn junction diode in reverse bias to operate in the breakdown region. The cbse is a prestigious educational board in india that conducts the final examinations for the class 12. Function of zener diode in voltage regulator seminar. Physics investigatory project on zener diode as a voltage.
The current, izm, of a zener diode is the maximum current that can flow through a zener diode at its rated voltage, vz. To draw the vi characteristic of zener diode and to determine zener breakdown voltage. To draw the characteristic curve of a zener diode and to determine its reverse breakdown voltage. With the help of a labeled circuit diagram explain the working of full wave rectifier and draw the input and output waveforms. Power is calculated by multiplying current by voltage pie, so we can calculate power dissipations for both the resistor and the zener diode quite easily. Cbse ncert notes class 12 physics semiconductor electronics. The relationship is obtained by applying kvl and it is vs vg r im. Breakdown voltage is also known as zener knee voltage. A diode can be defined as the fundamental electronic component that allows the flow of electricity in one direction only.
Physics semiconductors part 14 zener diode cbse class 12. Zener voltage v z is the reverse voltage at which breakdown occurs in a zener diode. V z0 is the voltage at which the straightline approximation of the iv characteristic intersects the horizontal axis. Draw iv characteristics of zener diode and explain the significance of breakdown voltage. Diodes zener diodes photodiodes optical isolation basic diode operation application. To draw the characteristic curve of a zener diode and to. Recipe for solving diode circuits state of diode is unknown before solving the circuit 1. Zener diode as a voltage regulator zener diode is a silicon semiconductor with a pn junction that is specifically designed to work in the reverse biased condition.
Zener diode definition, vi characteristics, and breakdown. The vi characteristic of zener diode indicates that characteristic of zener diode in forward bias is same as pn junction diode. Terry sturtevant electronics zener diodes and photodiodes. Typically there is also a minimum current required for the operation of the diode. This may moreover have an effect on the proper functioning of the digital tool. Ask questions, doubts, problems and we will help you. Jan 17, 2018 get ncert exemplar solutions for cbse class 12 physics, chapter 14 semiconductor electronics. Important questions for cbse class 12 physics semiconductor. The zener diode is a unique sort of diode having a sharp reduce off voltage for the duration of reverse biasing. Zener voltage v z is the reverse voltage at which breakdown occurs in a zener diode search logic. Zener diode is a reverse biased heavily doped semiconductor silicon or germanium pn junction diode, which is operated exclusively in the breakdown region. A zener diode is constructed for operation in the reverse breakdown region. Write down all circuit equations and simplify as much as possible 2. The topics and subtopics covered in semiconductor electronics.
Sep 10, 2016 pn junction and zener diode 12 class project. The circuit symbol of zener diode is as shown in the figure. Physics semiconductors part 14 zener diode cbse class 12 xii. We call this particular regulator circuit the shunt regulator. When a zener diode of zener voltage vz is connected in reverse direction parallel to the load, it maintains a constant voltage across the load equal to vz and hence stabilizes the output voltage. Explain zener breakdown and describe the use of a zener diode as a voltage regulator. Class12 cbse board zener diode learnnext offers animated video lessons with neatly explained examples, study material, free ncert solutions, exercises and tests. The zener diode working principles and its various. Thus, the increase or decrease in the input voltage results in increase or decrease of voltage drop across r s without any change in voltage across the zener diode. Function of zener diode in voltage regulator abstract the strength property which we use may not be capable to grant us normal voltage. Explain briefly, with the help of a circuit diagram, how a pn junction diode works as a half wave rectifier. In reverse bias, a negligible constant current flow through the zener diode but the current becomes abruptly large at certain voltage.
Semiconductor electronics important questions for cbse class 12 physics semiconductor, diode and its application 4. Dec 14, 2012 zener diode is a general purpose diode, which behaves like a normal diode when forward biased. Connections can be made as seen in the circuit diagram by clicking and dragging the mouse from one connecting terminal to the other connecting terminal of the devices to be connected. Zener diode is a general purpose diode, which behaves like a normal diode when forward biased. To see the circuit diagram, click on the showhide circuit diagram check box seen inside the simulator window. Jan 21, 2014 exp7 to draw characteristics of a zener diode and to determine its reverse breakdown voltage. A zener diode allows current to flow from its anode to its cathode like a normal semiconductor diode, but it also permits current to flow in the reverse direction when its zener voltage is reached.
L is equal to the zener breakdown voltage v zkregardless of the value of load resistor r l or source voltage v s provided, of course, that the zener diode is in breakdown. Zener diode is nothing but a single diode connected in a reverse bias mode and zener diode can be connected in reverse bias positive in a circuit as shown as picture. Products returned as matches will meet all specified criteria. Mar 08, 20 physics semiconductors part 14 zener diode cbse class 12 xii. At the minimize off voltage, it conducts to large values of cutting. Zener diodes are normal pn junction diodes operating in a reverse biased condition. It is made by doping both p and n sides of the junction heavily. Electrical characteristics tamb 25 c, unless otherwise specified part number zener voltage range 1 test current reverse leakage dynamic resistance f 1 khz surge current 3 regulator 2. Coed school kolar road bhoapl department of physics project report investigatoryproject on pn junction and diodes project report submitted by govind patel submitted to. User may specify either, both, or neither of the at least and no more than values.
Clamping basic diode operation reverse bias terry sturtevant electronics zener diodes and photodiodes. Zener diodes acts like normal pn junction diodes under forward biased condition. Clipping often its necessary to ensure that a signal does not exceed a. Applications of zener diodes voltage regulator, meter. Zener diode working with circuit diagram and applications. Coed school kolar road bhoapl department of physics project report investigatoryproject on pn junction and diodes project report submitted by govind patel submitted to mrs ratna hajela registerationno.
But when it is reverse biased above a certain voltage known as zener breakdown voltage or zener voltage or avalanche point or zener knee voltage the voltage remains constant for a wide range of current clarence zener is the scientist who discovered this electrical property. Physics investigatory project on zener diode as a voltage regulator 1. Physics mcqs for class 12 chapter wise with answers pdf download was prepared based on latest exam pattern. Many diodes described as zener diodes rely instead on avalanche breakdown. When forward biased, it behaves like a normal signal diode, but when the reverse voltage is applied to it, the voltage remains constant for a wide range of currents. The syllabus for the practical exam is designed by cbse according to the cce guidelines. This is an example of a primary application of zener diodes voltage regulation. Zener diode, voltmeter 02volt, voltmeter 030 volt, miliammeter, micro ammeter, variable source 02 volt and 030 volt. Zener diode fabrication zener diode is made by heavily doping of both p and ntype semiconductors and hence, the width of depletion layer becomes thin which lead to produce large electric field to increase the current even on applying reverse voltage of 4 or 5 v. Zener diode as a voltage regulator working principles. It also permits the current to flow in the reverse direction when the voltage is above a certain value known as the breakdown voltage. How is a zener diode fabricated so as to make it a special purpose diode. Cbse notes class 12 physics electronics aglasem schools.
Cbse physics lab manual for class 12 pdf download 10. A zener diode with small reverse breakdown voltage of about 6 volts, i. Exp7 to draw characteristics of a zener diode and to determine its reverse breakdown voltage. Get ncert exemplar solutions for cbse class 12 physics, chapter 14 semiconductor electronics. Dec 02, 2016 to draw the characteristic curve of a zener diode and to determine its reverse breakdown voltage. This way, zener diode behaves as a voltage regulator. Some of the important applications of a zener diodes are as a voltage regulator or stabilizer, as a meter protector and as a wave shaper. Working of the zener diode is similar to a pn junction diode in forward biased condition, but the uniqueness lies in the fact that it can also conduct when it is connected in reverse bias above its threshold breakdown voltage. Energy band in a crystal due to interatomic interaction, valence electrons of one atom are shared by more than one atom in the crystal. Zener diode symbol zener diode circuit zener diode vi characteristics zener diode working zener diode applications faqs. Class 12 cbse board zener diode videos, ncert solutions. Zener diodes when we first talked about practical diodes, it was mentioned that a parameter associated with the diode in the reverse bias region was the breakdown voltage, v br, also known as the peakinverse voltage piv. Both types are used with the zener effect predominating under 5.
The zener diode must have voltage greater than zener break down voltage v z. In figure given, assuming the diodes to be ideal ncert exemplar a d 1 is forward biased and d 2 is reverse biased and hence current flows from a to b. When forward biased voltage is applied to the zener diode it allows large amount of electric current and blocks only a small amount of electric current. A zener diode is a special type of device designed to operate in the zener breakdown region. The main use of zener diode lies in the fact that the voltage across a zener diode remains constant for a larger change in current. A pn junction diode can be utilized as a rectifier. Jun 17, 2015 physics investigatory project on zener diode as a voltage regulator 1. The maximum voltage that a junction diode can bear without break is called zener voltage and.
Explain how normal diodes might be used as crude substitutes for a zener diode in the following circuit. Use the diode equation for that state to solve the circuit equations and find i d and v d 3. In a dc circuit, zener diode can be used as a voltage regulator or to provide voltage reference. A zener diode is one in which the reverse breakdown occurs due to electron quantum tunneling under high electric field strength called zener effect. Diodes zener diodes photodiodes optical isolation application. A zener diode is a heavily doped silicon crystal diode which allows current to flow in the forward direction in the same manner as an ideal diode. Zener diode, photodiode, lightemitting diode, etc are specially designed pn. Applications of zener diodes zener diodes finds a wide applications commercially and industrially.
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