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. 38. Principle of Photo diode ? 45. 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. The core and the cladding have different optical characteristics. (vi) Core refractive index profile (step index or graded index). 21. 22. What is the difference between photovoltaic mode and photoconductive mode of operation of photo diode? 41. 13. 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. 32. This generated EMF is proportional to the frequency and intensity of the incident light. The leads of an LED should never be bent closer than about 2 mm from the encapsulation. Define what is zener voltage? Mention the applications of DIAC, SCR, LED and photoconductive cell. to the viva. Which material is mostly used for PIN and APDs ? 1. The voltage at which the zener diode breaks down is called the zener voltage. Q.3 Define the illuminating power and intensity of illumination. Photodiode is a photovoltaic device as well as a photoconductive device. Try to anticipate questions, comments and criticisms, and think how you would respond. 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. 46. Step-recovery diode is a voltage-dependent variable capacitor diode with graded doping profile (concentration of charge carriers decreasing near the junction). Card readers. 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. Viva questions are not to be written in the journal All rest of the matter is to be written as it is. 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. Define internal quantum efficiency of an LED? the photodiodes, when biased, must be operated in the reverse bias mode, i.e. Explain What Is An Ideal Diode? What does the laser wavelength depends upon ? 5. 1. Classification, Elements, Configuration of Data Ac... Data Acquisition System with Block Diagram. 16. Photodiode is a two-terminal semiconductor p-n junction diode device and is designed to operate with reverse bias. 2. Photodiode is a photovoltaic device or a photoconductive device or both? 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? 29. 21. 50 TOP SEMICONDUCTORS PN JUNCTION Theory Questions And. DIAC: 1. The large magnitude of current in power diodes leads to ohmic drop that hides the exponential part of the V-I characteristic curve. 12. 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. Your email address will not be published. Question 6. 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. When it is operated with a reverse bias, it is photoconductive device and when operated without the reverse bias, it is a photovoltaic device. 33. Figure 1. What is meant by the temperature coefficient? 9. Why is Schottky diode called hot-carrier diode? 15. Student makes corrections which are checked by examiners. The junction barrier is called the Schottky barrier. 40. Experiment Questions: 1.Experimently find out whether the given diode is made of Germanium or Silicon. 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. Explaining the Photoelectric Effect: The Concept of Photons. 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