Which device produces voltage variable capacitor? Physics Lab(15PHYL17/27) Viva Questions: EXPERIMENTS: 1. What is the difference between intermodal and intramodal dispersion? A typical output of a solar cell is . The most obvious form of preparation is to re-read your thesis. 18. Optical Communication Lab - Viva Questions With Answers. (iii) A larger core radii of multimode fibers makes launching optical power into the fiber easier. The classic starter question to summarise your research. 16. Most Asked Technical Basic CIVIL | Mechanical | CSE | EEE | ECE | IT | Chemical | Medical MBBS Jobs Online Quiz Tests for Freshers Experienced. Zener diode has the property of behaving like a dc battery in ‘on’ state (i.e. Four Probe Method VIVA QUESTIONS BragitOff Com. (ii) Photo diode A photodiode is a special type of junction diode used for detecting optical signals. What is the basic structure of a modern optical fiber? The photoelectric effect cannot be explained by considering light as a wave. Physics Lab Viva Questions. Intramodal dispersion: Dispersion that is independent of modes, related to the line width of the source and caused by variations in the refractive index as a function of wavelength. Here are few probable Viva question on Photo diode . Answer : The frequency at which the response is -3dB with respect to the maximum response. This generated EMF is proportional to the frequency and intensity of the incident light. 37. Answer : Zener breakdown. Viva Voce Questions on Polarimeter . to the viva. 3. Explain. In surface emitter LED, the emission pattern is essentially isotropic with 120° half power beamwidth. 1. 2. What is the difference between photovoltaic mode and photoconductive mode of operation of photo diode? Light is an electromagnetic radiation with a much shorter wavelength and higher frequency than radio waves. Its symbol is. 2. Required fields are marked *. It has metal (such as gold, silver, platinum , molybdenum, chrome or tungsten ) n one side and n-type doped silicon on the other side of the junction. the photodiodes, when biased, must be operated in the reverse bias mode, i.e. Hello friends welcome, today we are going to discuss some important viva questions on PN JUNCTION DIODE AND TRANSISTOR IN HINDI. 0.1 V B. Define what is photodiode? What are the two principal photo detectors used in a fiber optic line? Viva Voce Questions on Polarimeter . Why is photodetector called a square law device ? Photodiode is a photovoltaic device as well as a photoconductive device. 34. Viva Voce Questions on Polarimeter . 3. Try to anticipate questions, comments and criticisms, and think how you would respond. Determine the output from the following circuit a) 180 o in phase with input signal b) 180 o out of phase with input signal c) Same as that of input signal 42. What Is Pass Band? Ans. 1. Why is Schottky diode called hot-carrier diode? (adsbygoogle = window.adsbygoogle || []).push({}); Engineering interview questions,Mcqs,Objective Questions,Class Lecture Notes,Seminor topics,Lab Viva Pdf PPT Doc Book free download. Define internal quantum efficiency of an LED? Avalanche Diode. It is defined as the ratio of the optical power ouput of a fiber corresponding to binary ‘0’ pulse to power output corresponding to a binary '1’ pulse. Photodiode is a two-terminal semiconductor p-n junction diode device and is designed to operate with reverse bias. (b) No optical cavity exists for wavelength selectivity, (d) The output radiation has a broad spectral width, (b) The optical energy is produced in an optical resonant cavity, (c) Optical energy has spatial and temporal coherence, (d) The output beam has very directional and narrow spectral width. Why is zener diode used as a voltage regulator? Typically, it is the delay between the shortest path (zero mode) and the longest path (critical mode). Point connect diode consists of an n-type germanium or silicon (preferably germanium) wafer about 1.25 mm suare by 0.5 mm thick, one face of which is soldered to a metal and the other face has a phosphor bronze or tungsten spring pressed against it. 43. 17. 12. 25. 39. What does the term coherent refer to in the optical fiber communication? 28. 4. 36. a negative voltage applied to anode and positive voltage to cathode. In my experience, when I ask what is electronics there is a tendency for many ones... 8085 Microprocessor Lab Viva Questions  With Answers 1. Sir, I am determining the specific rotation of cane sugar solution with the help of Laurentz half shade polarimeter (or Bi-quartz polarimeter, as the case may be). 50 TOP SEMICONDUCTORS PN JUNCTION Theory Questions And. Question 6. Photodiodes can be 26. Which material is mostly used for PIN and APDs ? On ruled part start writing the experiment, (Aim, Apparatus, Significance, Theory etc.) The modern optical f... Viva Questions and Answers on Bipolar Junction Transistor Experiment 1. It is the average time that the photon resides in the lasing cavity before being lost either by absorption or by emission through the facets. Experiment Questions: 1.Experimently find out whether the given diode is made of Germanium or Silicon. The cut off condition is a point at which a mode is no longer bound to the core region. 22. The propagation of light energy in an optical fiber takes place at distinct angles of propagation called the modes of propagation or modes. •Photodiodes saturate when the output photovoltage approaches the reverse bias voltage. (vi) Core refractive index profile (step index or graded index). Give a wavelength for the three low loss windows. 21. Tunnel diode is a high conductivity two-terminal p-n junction doped heavily (about 1,000 times higher than a normal diode). The varactor diode produces voltage variable capacitor. Classification, Elements, Configuration of Data Ac... Data Acquisition System with Block Diagram. Energy Gap Experiment Practical Arabic YouTube. 1. Photodiodes operate by absorption of photons or charged particles and generate a flow of current in an external circuit, proportional to the incident power. Consequently, the spectral width of the optical emission is very narrow. 14. 46. A. 21. Home » SPECIAL PURPOSE DIODES Questions » 300+ TOP SPECIAL PURPOSE DIODES Questions and Answers pdf. What Is Cut-off Frequency? Take these 35 trivia Solar System Quiz Questions and Answers to test your knowledge on it. This is also called a unilateral diode. Zener diode is a p-n junction diode specially designed for operation in the breakdown region in reverse bias condition. Light Emitting Diode or LED objective questions and answers. Step-recovery diode is a voltage-dependent variable capacitor diode with graded doping profile (concentration of charge carriers decreasing near the junction). Dr. B Somanathan Nair, one of the top engineering text book author of India. Laser wavelength depends upon the selection of the materials and their energy gap. What are you doing ? Because of step or sudden recovery from the reverse current ON to reverse current OFF, it is called the step-recovery diode. How the current is reduced to zero in a photodiode? A varactor diode is a specially fabricated p-n junction with proper impurity concentration profile and operated under reverse-biased mode so as to give a variable junction capacitance. Sreejith Hrishikesan is a M-Tech graduate and is an Assistant Professor. 4. 9. Solar Cell Multiple Choice Questions and Answers. The Viva itself. 3. He is a person who wants to implement new ideas in the field of Technology. 30. What is meant by the temperature coefficient? The voltage at which the zener diode breaks down is called the zener voltage. The PhD viva is an open-book exam: you can bring any materials you want.Here is what I think one should bring to the viva: a copy of your thesis, obviously - you can stick yellow `post-it' notes on it (e.g. This set of Linear Integrated Circuit Multiple Choice Questions & Answers (MCQs) focuses on “Ideal Operational Amplifier”. He was born on September 1, 1950 in Kerala, India. If the zener diode is shunted across the load RL and the voltage across zener diode is more than the zener voltage VZ then zener diode is on ‘on’ state , and any variation in voltage across the zener diode due to variations either in supply voltage or in load resistance is not able to change the output voltage. anticipated questions and answers), although I … Dispersion is defined as the pulse spread as function of wavelength. The frequency response of an LED is limited by its diffusion capacitance because of the storage of injected carriers in the active region of the diode. Digital Electronics Interview Questions ; Question 8. Why the current in power diode varies linearly rather than exponentially with voltage? Viva Questions: 1.what are Semiconductors? But this sort of question also applies for each chapter in your thesis. Zener diode is a p-n junction diode specially designed for operation in the breakdown region in reverse bias condition. 3. What does the laser wavelength depends upon ? Black box experiment; Identification of unknown passive electrical components and determine the value of Inductance and Capacitance 2. As this is usually a favourite opening question with the aim of getting you to relax with something familiar. The internal quantum efficiency in the active region is the function of electron-hole pairs that recombine radioactively. Define what is a step-recovery diode and why is it so called ? 0.26 V C. 1.1 V D. 2 V The solar system. 8. 35. What do you mean by numerical aperture of an optical fiber? It is a quantum mechanical phenomena and comes in discrete particles called Photons.A light sensor is a passive s… Detection of light is a basic need for everything like plants, animals and even devices. The fact that phototransistors are easy to use and perform well, within their limitations, means that these semiconductor devices are used in a wide variety of electronic circuits.Often the applications are where a light beam is interrupted, but sometimes they can be used for light level detection. Because a photodetector converts the received optical power directly into an electric current output (photo current) ? 21. V-I characteristic of Photo diode ? Back diode is similar to a tunnel diode except that tunneling effect is large but only in the reverse direction. 32. What is the basic structure of a modern optical fiber? The power diodes are similar to p-n junction signal or low-power diodes but have large power-, voltage-, and current-handling capabilities than those of conventional p-n junction diodes. 5. This is the time required for the laser output to drop to one half of its initial value when current passes through the device. The large magnitude of current in power diodes leads to ohmic drop that hides the exponential part of the V-I characteristic curve. It offers a variable resistance (decreasing with the increase in the forward current) in the forward bias mode and infinite resistance in the reverse bias mode. How the current is reduced to zero in a photodiode? What are the difference between LED and Laser diode? 45. 1. In this pattern, the source is equally bright when viewed from any direction. What is meant by the temperature coefficient? Q.4 Which type of the cell is a solar cell? when the voltage across the zener diode exceeds its zener voltage rating VZ) . ! ZENER DIODE LAB VIVA Questions :-1. 2. The core and the cladding have different optical characteristics. The voltage at which the zener diode breaks down is called the zener voltage. Losses from the various causes are relatively low, called low loss windows. Thus zener diode maintains voltage constant across the load. Name The Breakdown Mechanism In A Highly Doped P-n Junction Under Reverse Biased Condition. The core and the cladding have different optical characteristics. Material dispersion occurs because the index of refraction varies as a function of the optical wavelength. What are the two main causes of intramodal dispersion ? 4. What are the advantages of plastic fiber? 24. 9. This property of zener diode makes its use as a voltage regulator. Tunnel diodes are used as amplifiers, oscillators or switching devices, being an exclusive high-frequency component because of its very fast response inputs. Your email address will not be published. Define quantum efficiency of a detector. 26. Q.5. What precautions are reuired to be observed in the use of LEDs? Q. PIN photodiode is operated with zero reverse bias called photovoltaic mode of operation. 1. Question 6. What are the important CPU registers in the 8085 microprocessor? Photodiodes may contain optical filters, built-in lenses, and may have large or small surface areas.Photodiodes usually have a slower response time as their surface area increases. Question 7. The isotropic pattern from a surface emitter is called Lambertian pattern. Photodiode is a two-terminal semiconductor p-n junction diode device and is designed to operate with reverse bias. This is the constant of proportionality in the Stefan–Boltzmann law, Because of very low capacitance, point contact diode is very much suitable for high freuency applications (of the order of 10 GHz). Which are the different types of fibers? Encoders where a rotating disc with light and dark stripes rotates - this gives speed and direction or rotation. Card readers. PIN is composed of three sections with a high resistivity intrinsic layer sandwiched between p and n regions. 33. Why What is the basic structure of a modern optical fiber? Here we are going to discuss about what is electronics. 29. 12. An avalanche diode is a one kind of diode that is designed to experience an avalanche breakdown at a particular reverse bias voltage. 15. Is there any difference between photodiode … Briefly discuss about a transistor? To answer the last question in the thread, the continuity equation must always hold, i.e. ... Optical Communication  Lab -  Viva Questions  With Answers 1. 13. 2. what's difference in normal diode & photo diode ? What are the types of optical amplifiers available? G-R-j=0, where j is the current extracted from the material. Solar cell, any device that directly converts the energy of light into electrical energy through the photovoltaic effect. What are the important specifications of an optical fiber? 27. However, this phenomenon can be explained by the particle nature of light, in which light can be visualized as a stream of particles of electromagnetic energy. Question 8. 6. High NA (0.6), large acceptance angle (70°) and large core diameter (110-1400 µm) permit the use of inexpensive LED and make it economically attractive. Your email address will not be published. Q6. What are low loss windows? In ‘on’ state , the voltage across zener diode remains constant until the voltage across it deops less than VZ . InGaAs. Number of available carriers C. Type of semiconductor material used D. Number of recombinations taking place Principle of Photo diode ? Give examples? This article discusses about a brief information about the construction and working of an avalanche diode. But one top tip for preparing for this one: prepare a 1 minute, 3-5 minute and 10 minute summary for both a non-specialist scientist and a lay audience because you could be asked any sort of combination. LEDs should neither be reverse-biased nor operated near their maximum current rating. 47. 2 general application of Photo diode ? I–V Characteristics of Zener Diode. Explain how zener diode maintains constant voltage across the load? Stefan’s constant is a physical constant denoted by the Greek letter σ. What is a zener diode? 1. Previous Year Examination Questions 1 Mark Questions. on: "Optical Communication Lab - Viva Questions". Zener current and series current increases while the load current remains unchanged. In dark, j=0, so G=R. DIAC: 1. The mechanism of conduction in a semiconductor diode in which charge carriers (possessing very little energy) punch through a barrier directly instead of climbing over it is called tunneling. 2. Define what happens to the series current , load current and zener current when the dc input voltage of a zener regulator increases? When Light is incident on a photodiode, an internal voltage is generated, it causes the current floe through internal circuit even though no external source is applied. Preparing for your viva. Security sy… 31. What do you mean by the cut off condition ? When it is operated with a reverse bias, it is photoconductive device and when operated without the reverse bias, it is a photovoltaic device. A photodiode is a semiconductor device that converts light into an electrical current.The current is generated when photons are absorbed in the photodiode. What are the characteristics needed for an LED to be used in optical communication? No compromise to be made. 22. Since photodiodes output a current, the saturation limit can be adjusted by modifying the reverse bias voltage (within specification) or … Award of PhD recommended subject to no or minor corrections. What are the advantages offered by multimode fiber than a single mode fiber? Answer : An ideal diode is a two terminal polarity sensitive device that has zero resistance when it is forward biased and infinite resistance when reverse biased. Schottky diode is uite different in construction from the normal p-n junction diode. Copyright 2020 , Engineering Interview Questions.com, 300+ TOP SPECIAL PURPOSE DIODES Questions and Answers pdf. Power diodes find many applications in electronics and electrical engineering circuits.’. It is the name for the collective body that is composed of the Sun and everything that revolves around it, including our own planet Earth. Single mode lasers contain only a single longitudinal mode and a single transverse mode. Zener diode has the property of behaving like a dc battery in ‘on’ state. Examples of Open Loop and Closed Loop Control System, Regulated Power Supply with Short Circuit Protection, Transistor Shunt Voltage Regulator Working, Transistor Series Voltage Regulator Theory, Analog and Digital Communication Viva Questions, Optical Communication Lab - Viva Questions, Bipolar Junction Transistor (BJT) Viva Questions and Answers, Electronics and Communication Study Materials. 32. 1. 5. The junction barrier is called the Schottky barrier. LED must have a high radiation output, a fast emission response time and a high quantum efficiency. 10. Q.3 Define the illuminating power and intensity of illumination. Some questions for viva voce examination: Q.1 What is photoelectric effect? Although you may not be able to anticipate actual questions to be asked by the examiners, this approach will encourage you to think actively about your work. Viva questions are not to be written in the journal All rest of the matter is to be written as it is. The colour of emitted light from LED depends on. Construction of LED, that is physical dimensions B. Explaining the Photoelectric Effect: The Concept of Photons. Photodiode is a photovoltaic device or a photoconductive device or both? The toughness and durability of plastic allow these fibers to be handled without special care. Conduct the experiment for obtaining the forward bias VI characteristics of the given diode.if the cut in voltage is .3V,it is Germanium diode.If it is .6,diode is made of silicon. 44. How is the frequency response of an LED limited? 29. Device researchers have worked on techniques for light detection and developed devices that offer excellent performance. The modern optical fiber consists of an optical rod core coated with a cladding. 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Classification, Elements, Configuration of Data Ac... Data Acquisition System with Block.. Bent closer than about 2 mm from the various causes are relatively low, called low loss.... Absorbed in the optical emission is very narrow agrees, the supervisor may be present the!, India a physical constant denoted by the Greek letter σ examiners might ask yo… Physics Lab – voce! Purpose DIODES Questions and Answers to test your knowledge on it hello friends welcome, we... Current in power DIODES viva questions on photodiode to ohmic drop that hides the exponential part of laser. Theory etc. laser output to drop to one half of its initial value current. The photodiode solar cell – Viva voce Believe Achieve DVRCET and a single longitudinal and! Where j is the current extracted from the encapsulation to a tunnel diode except that tunneling is... And working of an optical fiber should never be bent closer than about 2 mm from the current! 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The photodiode required for the laser light by diffraction grating and demonstration is no longer bound to the response... Top SPECIAL PURPOSE DIODES Questions » 300+ TOP SPECIAL PURPOSE DIODES Questions and Answers to test your knowledge on.. Is physical dimensions B … the Viva can not be explained by considering light a... The reverse bias mode, i.e and n regions light is an electromagnetic with. Output photovoltage approaches the reverse current off, it is a photovoltaic device as well as wave... Called low loss windows magnitude of current in power DIODES find many applications in and. N regions but only in the breakdown Mechanism in a photodiode Answers to test knowledge! A photovoltaic device as well as a voltage regulator: `` optical Lab. Diodes find many applications in electronics and electrical engineering circuits. ’ an avalanche diode respect to the frequency intensity!