Exam Paper: Electrical Science & Circuits 1, BEng in Electronic Engineering, CIT, 2011, Exams of Electrical Engineering

Download Exam Paper: Electrical Science & Circuits 1, BEng in Electronic Engineering, CIT, 2011 and more Exams Electrical Engineering in PDF only on Docsity! Page 1 of 3 CORK INSTITUTE OF TECHNOLOGY INSTITIÚID TEICNEOLAÍOCHTA CHORCAÍ Semester 2 Examinations 2010/11 Module Title: Electrical Science and Circuits 2 Module Code: ELTR6010 School: Electrical & Electronic Engineering Programme Title: Bachelor of Engineering in Electronic Engineering – Year 1 Programme Code: EELXE_7_Y1 External Examiner(s): Dr. A. Donnellan, Mr. I. Kennedy Internal Examiner(s): Mr. Michael Murray Instructions: Answer FOUR questions Duration: 2 hours Sitting: Summer 2011 Requirements for this examination: Note to Candidates: Please check the Programme Title and the Module Title to ensure that you have received the correct examination paper. If in doubt please contact an Invigilator. Page 2 of 3 Q1. (a) Three capacitors of value 2µF, 4µF and 4µF respectively are connected (i) in series and (ii) in parallel across a 48V DC supply. Calculate for each case: i. The equivalent capacitance ii. The voltage and charge on each capacitor. iii. The energy stored in each circuit. [18 marks] (b) A capacitor has a surface area of 1mm 2 and a dielectric thickness of 0.1mm. If the permittivity of the dielectric is 40 X 10 -6 F/M, calculate the value of capacitance. [7 marks] Q2. (a) Describe, with the aid of a diagram, how the dimensions and materials of a capacitor influence its operation. [6 marks] (b) A capacitor of value 100µF is connected in series with a resistance of 100Ω across a DC supply of 100V. Find (i) the time constant of the circuit and (ii) the current after 10 mS. Illustrate the current through the capacitor as a function of time. [13 marks] (c) Describe an application where a capacitor may be used. [6 marks] Q3. (a) Describe and illustrate how a motor could be built and outline the parameters which determine the speed of the motor. [10 marks] (b) A DC permanent magnet motor having a coil of length 20cm with 1000 turns is to exert a maximum rotation force of 1N. If the magnetic flux is 2mT, estimate the current which must flow in the coil. [ 7 marks] (c) Describe with the aid of a diagram, the construction and operation of a transformer. Give some examples of transformer applications. [8 marks]