Daffodil International University Department of Computer Science and Engineering Faculty of Science & Information Technology Midterm Examination, Spring 2021 @ DIU Blended Learning Center Course Code: CSE212 (Day), Course Title: Basic Electronics Level: 2 Term: 1 Section: J, K Teacher: MHK Modality: Online Open Book Exam Date: Tuesday, 9 March 2021 Time: 9:00-11:30am Two hrs and Thirty mins (2:30) to support online open/case study based assessment Marks: 25 Directions: • Students need to go through the CASE STUDY shown in this exam paper. • Analyze and answer specific section based on your own thinking and work. • Do not share as this will be treated as plagiarism by Blended Learning Center. • The pdf file name must be CSE212_Your Section_Your ID. Answer all the following three questions Q1. We all know the name of motherboard. Every Laptop, Computer, Smartphone has 5 motherboard. Motherboard uses various types of electronics devices and circuits. The electronics devices are made by semiconductors. One of the most common semiconductors is available in the natural environment. One of the important properties of semiconductors is related to temperature. a. In room temperature, commonly used semiconductors can’t produce adequate electricity for any practical use, then what should we do? b. Motherboard uses various voltage levels in different circuits, which electronics devices may help in this case? c. To operate the pn junction, we have some limitations, mention them. Q2. Suppose you are an engineer of a robotics project. Robots need pure dc supply like laptop. 5+5 Unfortunately the power supply is 220V, 50Hz ac. The electronic circuits may help you. We =10 have studied a number of electronic circuits. You have to design those circuits, so try to remember them. It will help you to get a job at that reputed robotics company. a. Suppose you have a piece of impure semiconductor, describe the procedure to produce the first electronics device from it. Also show the forward current and voltage, reverse current and voltage, knee voltage, breakdown voltage etc. b. Which electronics device/devices and circuits may help us to operate the robot efficiently and smoothly? Describe the best circuits only. Q3. I. In a hot humid day, suddenly the power demands increased. One of the power plant of 6+4 power supply company has shut down, as a result, the transformer secondary supply voltage =10 decreased (where, v=200sinωt, f=50Hz). At that time, due to sudden shut down of all the Air Conditioners (AC) of the DIU city campus, the supply voltage of the desktop computers (PCs) increase. To protect our sophisticated valuable electronic equipment/devices from this sort of voltage fluctuation, we use various types of electronics devices and circuits. If the forward resistances of the diodes are 25Ω each, the load of the best rectifier circuit used to generate pulsating dc (pdc) is 175Ω and the Transformer ratio is 10:1, then a. What will be the output voltage? b. Find out the efficiency. c. Find out the PIV and output frequency. II. If we use the worst rectifier then, a. Find out the efficiency. b. Find out the PIV and output frequency.
