Q.2 What is a photo cell? 30. Good Luck! 2 general application of Photo diode ? 34. 28. Mention the applications of DIAC, SCR, LED and photoconductive cell. What are you doing ? Draw the symbol of photo diode ? Briefly discuss about a transistor? 15. Semiconductor Laser Amplifier (SLA), Fiber Raman Amplifier (FRA), Fiber Brillouin Amplifier (FBA), Rare Earth ion Doped Fiber Amplifier. Take these 35 trivia Solar System Quiz Questions and Answers to test your knowledge on it. How is the frequency response of an LED limited? 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. the photodiode as the incident optical power increases. I–V Characteristics of Zener Diode. 1. How the voltage variable capacitance varies with the change in voltage across it? The Viva Examiners viva student after a pre-viva meeting. Viva questions are not to be written in the journal All rest of the matter is to be written as it is. Define what happens to the series current , load current and zener current when the dc input voltage of a zener regulator increases? Give examples? Why the current in power diode varies linearly rather than exponentially with voltage? Stefan’s constant is a physical constant denoted by the Greek letter σ. ! The classic starter question to summarise your research. Ans. ... Optical Communication  Lab -  Viva Questions  With Answers 1. 1. 17. What are the applications of tunnel diodes? LEDs should neither be reverse-biased nor operated near their maximum current rating. What are the important CPU registers in the 8085 microprocessor? Is there any difference between photodiode … 1. The colour of emitted light from LED depends on. Zener current and series current increases while the load current remains unchanged. An avalanche diode is a one kind of diode that is designed to experience an avalanche breakdown at a particular reverse bias voltage. What are the types of optical amplifiers available? The modern optical fiber consists of an optical rod core coated with a cladding. The junction barrier is called the Schottky barrier. 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. The effect, that causes the output pulse to be wider than the input pulse. What does the laser wavelength depends upon ? Security sy… Copyright 2020 , Engineering Interview Questions.com, 300+ TOP SPECIAL PURPOSE DIODES Questions and Answers pdf. In my experience, when I ask what is electronics there is a tendency for many ones... 8085 Microprocessor Lab Viva Questions  With Answers 1. 2. Light is an electromagnetic radiation with a much shorter wavelength and higher frequency than radio waves. Digital Electronics Interview Questions ; Question 8. Construction of LED, that is physical dimensions B. Principle of Photo diode ? This article discusses about a brief information about the construction and working of an avalanche diode. 100 TOP ELECTRONICS Amp GRANADA Leitor Formato ... Photodiode Characteristics And Applications. This is the time required for the laser output to drop to one half of its initial value when current passes through the device. 12. But this sort of question also applies for each chapter in your thesis. DIAC: 1. Name The Breakdown Mechanism In A Highly Doped P-n Junction Under Reverse Biased Condition. 4. 22. The voltage at which the zener diode breaks down is called the zener voltage. 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. 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. Which device produces voltage variable capacitor? Define what is a step-recovery diode and why is it so called ? Experiment Questions: 1.Experimently find out whether the given diode is made of Germanium or Silicon. Q.5. In surface emitter LED, the emission pattern is essentially isotropic with 120° half power beamwidth. the photodiodes, when biased, must be operated in the reverse bias mode, i.e. Consequently, the spectral width of the optical emission is very narrow. PIN is composed of three sections with a high resistivity intrinsic layer sandwiched between p and n regions. 13. 2. 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. The junction capacitance of a varactor diode varies inversely as the square root of the reverse bias voltage in case of alloyed junction and varies inversely as the cube root of reverse bias voltage for diffuse junction. 43. 2. what's difference in normal diode & photo diode ? Classification, Elements, Configuration of Data Ac... Data Acquisition System with Block Diagram. What is the difference between intermodal and intramodal dispersion? 50 TOP SEMICONDUCTORS PN JUNCTION Theory Questions And. LED must have a high radiation output, a fast emission response time and a high quantum efficiency. What type of material is used in the detector for regions 800-900 nm and 1100-1600 nm? Viva Voce Questions on Polarimeter . What is the basic structure of a modern optical fiber? 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. 9. 37. 38. G-R-j=0, where j is the current extracted from the material. Because a photodetector converts the received optical power directly into an electric current output (photo current) ? 29. This material can absorb light with wavelength as long as 1650 nm. What are the two main causes of intramodal dispersion ? Tunnel diode is a high conductivity two-terminal p-n junction doped heavily (about 1,000 times higher than a normal diode). The modern optical f... Viva Questions and Answers on Bipolar Junction Transistor Experiment 1. How the current is reduced to zero in a photodiode? What is meant by the temperature coefficient? Energy Gap Experiment Practical Arabic YouTube. On ruled part start writing the experiment, (Aim, Apparatus, Significance, Theory etc.) 21. 21. In ‘on’ state , the voltage across zener diode remains constant until the voltage across it deops less than VZ . Question 6. 2. anticipated questions and answers), although I … 26. 14. Figure 1. 5. Here are few probable Viva question on Photo diode . Define internal quantum efficiency of an LED? Which material is mostly used for PIN and APDs ? 25. 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. It is a reverse biased p-n junction made from a photosensitive material. 8. Question 7. Its symbol is. InGaAs. Since in forward bias operation of the Schottky diode, the electrons on the n-side gains enough energy to cross the junction and plunge into the metal with very large energy, they are usually called into the metal with very large energy, they are usually called hot carriers and the diode is called hot-carrier diode. A typical output of a solar cell is . Try to anticipate questions, comments and criticisms, and think how you would respond. The core and the cladding have different optical characteristics. What is meant by the temperature coefficient? Encoders where a rotating disc with light and dark stripes rotates - this gives speed and direction or rotation. Answer : Passband is the range of frequencies or wavelengths that can pass through a filter without being attenuated. 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. Define what is zener voltage? How the current is reduced to zero in a photodiode? 3. 16. Your email address will not be published. What are the basic performance criteria of the WDM technique ? Zener diode has the property of behaving like a dc battery in ‘on’ state (i.e. Zener diode is a p-n junction diode specially designed for operation in the breakdown region in reverse bias condition. Series and parallel LCR Circuits (Determination of resonant frequency and quality factor) 3. 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. Avalanche Diode. The varactor diode produces voltage variable capacitor. Explain What Is An Ideal Diode? 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. 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. PIN photodiode is operated with zero reverse bias called photovoltaic mode of operation. The internal quantum efficiency in the active region is the function of electron-hole pairs that recombine radioactively. 46. 5. 0.1 V B. Why The effect of temperature on zener voltage is given in terms of temperature coefficient which is defined as the percentage change in nominal zener voltage for each degree centigrade of change in junction temperature. Because of step or sudden recovery from the reverse current ON to reverse current OFF, it is called the step-recovery diode. Q6. Dispersion is defined as the pulse spread as function of wavelength. (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. What are the two principal photo detectors used in a fiber optic line? What Is Cut-off Frequency? Which are the different types of fibers? Question 7. Back diode is similar to a tunnel diode except that tunneling effect is large but only in the reverse direction. Explain how zener diode maintains constant voltage across the load? Previous Year Examination Questions 1 Mark Questions. What are the advantages offered by multimode fiber than a single mode fiber? Viva usually arranged by supervisor or other member of supervisor’s Department. What are the difference between LED and Laser diode? Solar Cell Multiple Choice 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). Why is zener diode used as a voltage regulator? 18. Number of available carriers C. Type of semiconductor material used D. Number of recombinations taking place This generated EMF is proportional to the frequency and intensity of the incident light. Viva Voce Questions on Polarimeter . 3. The modern optical fiber consists of an optical rod core coated with a cladding. 24. In this pattern, the source is equally bright when viewed from any direction. Card readers. Why is photodetector called a square law device ? As this is usually a favourite opening question with the aim of getting you to relax with something familiar. 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. Viva Questions Determine the wavelength of the laser light by diffraction grating and demonstration. Because of very low capacitance, point contact diode is very much suitable for high freuency applications (of the order of 10 GHz). 1. This is also called a unilateral diode. 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 Explaining the Photoelectric Effect: The Concept of Photons. Answer : The frequency at which the response is -3dB with respect to the maximum response. Solar cell, any device that directly converts the energy of light into electrical energy through the photovoltaic effect. 27. V-I characteristic of Photo diode ? a negative voltage applied to anode and positive voltage to cathode. Q.4 Which type of the cell is a solar cell? 34. 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. 26. The voltage at which the zener diode breaks down is called the zener voltage. 42. Sreejith Hrishikesan is a M-Tech graduate and is an Assistant Professor. 5. Single mode lasers contain only a single longitudinal mode and a single transverse mode. Multiple Choice Questions and Answers on Optical Fiber Communication(Part-1) Multiple Choice Questions and Answers By Sasmita January 9, 2020 1) In an optical fiber communication system, which among the following is not a typical transmitter function? What are the characteristics needed for an LED to be used in optical communication? Black box experiment; Identification of unknown passive electrical components and determine the value of Inductance and Capacitance 2. The most obvious form of preparation is to re-read your thesis. Material dispersion occurs because the index of refraction varies as a function of the optical wavelength. 45. Four Probe Method VIVA QUESTIONS BragitOff Com. What do you mean by numerical aperture of an optical fiber? 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. Required fields are marked *. 36. Photodiode Characteristics and Applications 5 Silicon photodiodes are semiconductor devices responsive to high-energy particles and photons. Photodiode is a two-terminal semiconductor p-n junction diode device and is designed to operate with reverse bias. 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). 2. Before venturing into each chapter, your examiners might ask yo… The leads of an LED should never be bent closer than about 2 mm from the encapsulation. 44. Viva Questions: 1.what are Semiconductors? 32. 3. Optical Communication Lab - Viva Questions With Answers. Detection of light is a basic need for everything like plants, animals and even devices. What is the basic structure of a modern optical fiber? (iii) A larger core radii of multimode fibers makes launching optical power into the fiber easier. Typically, it is the delay between the shortest path (zero mode) and the longest path (critical mode). Tunnel diodes are used as amplifiers, oscillators or switching devices, being an exclusive high-frequency component because of its very fast response inputs. 32. Some questions for viva voce examination: Q.1 What is photoelectric effect? The propagation of light energy in an optical fiber takes place at distinct angles of propagation called the modes of propagation or modes. No compromise to be made. 46. Define quantum efficiency of a detector. Dr. B Somanathan Nair, one of the top engineering text book author of India. He was born on September 1, 1950 in Kerala, India. Explain. Thus zener diode maintains voltage constant across the load. when the voltage across the zener diode exceeds its zener voltage rating VZ) . Schottky diode is uite different in construction from the normal p-n junction diode. This property of zener diode makes its use as a voltage regulator. What precautions are reuired to be observed in the use of LEDs? Losses from the various causes are relatively low, called low loss windows. 2. To answer the last question in the thread, the continuity equation must always hold, i.e. The solar system. 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. Planar diffused silicon photodiode n PRINCIPLE OF OPERATION Silicon is a semiconductor with a band gap energy of 1.12 eV at 19. ZENER DIODE LAB VIVA Questions :-1. 10. to the viva. The toughness and durability of plastic allow these fibers to be handled without special care. Question 6. Viva Question For Band Gap Physics Lab – Viva Voce Believe Achieve DVRCET. Photodiodes operate by absorption of photons or charged particles and generate a flow of current in an external circuit, proportional to the incident power. Q.3 Define the illuminating power and intensity of illumination. Define what is photodiode? Here we are going to discuss about what is electronics. Give a wavelength for the three low loss windows. What are the advantages of plastic fiber? 39. What do you mean by the cut off condition ? •Photodiodes saturate when the output photovoltage approaches the reverse bias voltage. Your email address will not be published. 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. He is a person who wants to implement new ideas in the field of Technology. 47. (vi) Core refractive index profile (step index or graded index). 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. If the student agrees, the supervisor may be present at the viva. Viva Voce Questions on Polarimeter . Device researchers have worked on techniques for light detection and developed devices that offer excellent performance. 12. 1. 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. Into the fiber easier explaining the photoelectric effect can not be explained by considering as... Junction TRANSISTOR experiment 1 ( MCQs ) focuses on “ Ideal Operational Amplifier ” resistivity layer. Output to drop to one half of its very fast response inputs these fibers to observed... Fiber optic line absorbed in the photodiode ( vi ) core refractive index (! Ideas in the optical wavelength as 1650 nm voce Believe Achieve DVRCET,. Member of supervisor ’ s constant is a p-n junction diode a M-Tech graduate and is designed to with. Absorb light with wavelength as long as 1650 nm devices responsive to high-energy particles and photons large. 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Answer: Passband is the function of the V-I characteristic curve responsive to particles. Light as a function of electron-hole pairs that recombine radioactively internal quantum efficiency in the optical consists. Constant denoted by the delay between different modes current passes through the device on September 1, 1950 in,. Semiconductor devices responsive to high-energy particles and photons V-I characteristic curve in HINDI wavelengths can! That causes the output pulse to be handled without SPECIAL care is reduced to zero in a photodiode of. Volume is R. Intermodal dispersion: dispersion caused by the Greek letter σ by supervisor or other member of ’. Which material is mostly used for pin and APDs illuminating power and intensity of illumination where rotating. Fibers to be handled without SPECIAL care different modes what precautions are reuired to written! Student after a pre-viva meeting with the aim of getting you to relax with familiar. The student agrees, the voltage at which a mode is no longer bound the... Welcome, today we are going to discuss some important Viva Questions not... To experience an avalanche breakdown at a particular reverse bias this article about! V-I characteristic curve power diode varies linearly rather than exponentially with voltage R. Intermodal dispersion: dispersion caused by cut! Power diode varies linearly rather than exponentially with voltage by supervisor or other member of supervisor s. In ‘ on ’ state, the spectral width of the matter is be! Dispersion is defined as the pulse spread as function of electron-hole pairs that recombine radioactively specially designed operation... Losses from the various causes are relatively low, called low loss windows discuss about what the! A two-terminal semiconductor p-n junction diode Amp GRANADA Leitor Formato... photodiode characteristics and applications 5 photodiodes!