This may moreover have an effect on the proper functioning of the digital tool. 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. 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. 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. 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. The zener diode must have voltage greater than zener break down voltage v z. Get ncert exemplar solutions for cbse class 12 physics, chapter 14 semiconductor electronics. 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.
Draw iv characteristics of zener diode and explain the significance of breakdown voltage. We call this particular regulator circuit the shunt regulator. Class12 cbse board zener diode learnnext offers animated video lessons with neatly explained examples, study material, free ncert solutions, exercises and tests. Explain how normal diodes might be used as crude substitutes for a zener diode in the following circuit. Function of zener diode in voltage regulator seminar. The topics and subtopics covered in semiconductor electronics. Zener voltage v z is the reverse voltage at which breakdown occurs in a zener diode search logic. Physics mcqs for class 12 chapter wise with answers pdf download was prepared based on latest exam pattern. Physics investigatory project on zener diode as a voltage regulator 1. The relationship is obtained by applying kvl and it is vs vg r im. To draw the characteristic curve of a zener diode and to. Dec 02, 2016 to draw the characteristic curve of a zener diode and to determine its reverse breakdown voltage. Important questions for cbse class 12 physics semiconductor. 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.
Zener diode is a general purpose diode, which behaves like a normal diode when forward biased. At the minimize off voltage, it conducts to large values of cutting. Both types are used with the zener effect predominating under 5. Use the diode equation for that state to solve the circuit equations and find i d and v d 3.
Typically there is also a minimum current required for the operation of the diode. Mar 08, 20 physics semiconductors part 14 zener diode cbse class 12 xii. 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. In reverse bias, a negligible constant current flow through the zener diode but the current becomes abruptly large at certain voltage. This was a bad thing before the whole avalanche breakdown, large current. Cbse physics lab manual for class 12 pdf download 10. A zener diode is a special type of device designed to operate in the zener breakdown region. Exp7 to draw characteristics of a zener diode and to determine its reverse breakdown voltage. It also permits the current to flow in the reverse direction when the voltage is above a certain value known as the breakdown voltage. Recipe for solving diode circuits state of diode is unknown before solving the circuit 1.
With the help of a labeled circuit diagram explain the working of full wave rectifier and draw the input and output waveforms. The cbse is a prestigious educational board in india that conducts the final examinations for the class 12. Jun 17, 2015 physics investigatory project on zener diode as a voltage regulator 1. A zener diode is constructed for operation in the reverse breakdown region.
A diode can be defined as the fundamental electronic component that allows the flow of electricity in one direction only. Zener diode working with circuit diagram and applications. The zener diode working principles and its various applications. 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. Physics investigatory project on zener diode as a voltage. 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. 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. 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. 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.
Diodes zener diodes photodiodes optical isolation basic diode operation application. Applications of zener diodes voltage regulator, meter. Zener diode, photodiode, lightemitting diode, etc are specially designed pn. Zener diode, voltmeter 02volt, voltmeter 030 volt, miliammeter, micro ammeter, variable source 02 volt and 030 volt. To see the circuit diagram, click on the showhide circuit diagram check box seen inside the simulator window. Ncert exemplar solutions, cbse 12th physics, chapter 14. User may specify either, both, or neither of the at least and no more than values. Zener diode as a voltage regulator working principles.
To draw the characteristic curve of a zener diode and to determine its reverse breakdown voltage. V z0 is the voltage at which the straightline approximation of the iv characteristic intersects the horizontal axis. Jan 17, 2018 get ncert exemplar solutions for cbse class 12 physics, chapter 14 semiconductor electronics. Class 12 cbse board zener diode videos, ncert solutions. A pn junction diode can be utilized as a rectifier. The zener diode working principles and its various. Energy band in a crystal due to interatomic interaction, valence electrons of one atom are shared by more than one atom in the crystal. In a dc circuit, zener diode can be used as a voltage regulator or to provide voltage reference. Breakdown voltage is also known as zener knee voltage. Write down all circuit equations and simplify as much as possible 2.
The zener diode is a unique sort of diode having a sharp reduce off voltage for the duration of reverse biasing. 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. 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. 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. The syllabus for the practical exam is designed by cbse according to the cce guidelines. Zener diodes are generally employed in multimeters to protect the meter movement against the damage from the accidental overloads. Function of zener diode in voltage regulator abstract the strength property which we use may not be capable to grant us normal voltage.
Terry sturtevant electronics zener diodes and photodiodes. Physics semiconductors part 14 zener diode cbse class 12 xii. Use the diode equation for that state to solve the circuit equations and find i. The maximum voltage that a junction diode can bear without break is called zener voltage and. 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. Zener diodes acts like normal pn junction diodes under forward biased condition. Explain briefly, with the help of a circuit diagram, how a pn junction diode works as a half wave rectifier. Zener designed a pn junction diode in reverse bias to operate in the breakdown region. 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. This is an example of a primary application of zener diodes voltage regulation. Jan 21, 2014 exp7 to draw characteristics of a zener diode and to determine its reverse breakdown voltage. Products returned as matches will meet all specified criteria. Part of made in india, design innovation workshop,2015 a fresh new experience in project.
Many diodes described as zener diodes rely instead on avalanche breakdown. 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. The maximum voltage that a junction diode can bear without break is called zener voltage and the junction diodes possessing this voltage is known as zener diode. A zener diode with small reverse breakdown voltage of about 6 volts, i. Zener diodes are normal pn junction diodes operating in a reverse biased condition. Jan 22, 2020 free pdf download of cbse physics multiple choice questions for class 12 with answers chapter 14 semiconductor electronics. Zener diode is a reverse biased heavily doped semiconductor silicon or germanium pn junction diode, which is operated exclusively in the breakdown region. The current through pn junction flow only from p toward n and not from n toward p. Semiconductor electronics important questions for cbse class 12 physics semiconductor, diode and its application 4. It is made by doping both p and n sides of the junction heavily.
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. 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. 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. Clamping basic diode operation reverse bias terry sturtevant electronics zener diodes and photodiodes. Explain zener breakdown and describe the use of a zener diode as a voltage regulator. Dec 14, 2012 zener diode is a general purpose diode, which behaves like a normal diode when forward biased. Zener diode symbol zener diode circuit zener diode vi characteristics zener diode working zener diode applications faqs.
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. Coed school kolar road bhoapl department of physics project report investigatoryproject on pn junction and diodes project report submitted by govind patel submitted to. Applications of zener diodes zener diodes finds a wide applications commercially and industrially. 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. Ask questions, doubts, problems and we will help you. Sep 10, 2016 pn junction and zener diode 12 class project. To draw the vi characteristic of zener diode and to determine zener breakdown voltage.
Example zener diode circuit analysis blank ku ittc. Clipping often its necessary to ensure that a signal does not exceed a. Cbse notes class 12 physics electronics aglasem schools. Diodes zener diodes photodiodes optical isolation application. Cbse ncert notes class 12 physics semiconductor electronics. Zener diode definition, vi characteristics, and breakdown. The current, izm, of a zener diode is the maximum current that can flow through a zener diode at its rated voltage, vz. The vi characteristic of zener diode indicates that characteristic of zener diode in forward bias is same as pn junction diode.