LH29 SCHOOL OF SPORT AND BIOMEDICAL SCIENCE BEng (HONS)/MEng BIOMEDICAL ENGINEERING BEng (HONS) MEDICAL ENGINEERING SEMESTER 2 EXAMINATIONS 2015/2016 MODULE NO: BME4004 Date: Wednesday 18 May 2016 Time: 2.00 pm 4.00 pm INSTRUCTIONS TO CANDIDATES: There are five questions. Answer ANY FOUR questions. All questions carry equal marks. Marks for parts of questions are shown in brackets. Electronic calculators may be used provided that data and program storage memory is cleared prior to the examination. CANDIDATES REQUIRE: Formula Sheet (attached).
Page 2 of 7 Q1 a) Define the superposition principle. b) Apply the superposition principle to the following voltage-divider (Figure Q1) in order to find Vp (10 marks) Figure Q1 c) A straight wire carries a current of 3 A. What is the magnetic field strength H at a distance of 100 mm from the wire? d) A 10 F capacitor has 12 V across it. What quantity of charge is stored in it?
Page 3 of 7 Q2 a) Define Kirchhoff s voltage and current law. b) Define the Thevenin s and Norton s equivalent circuits. (4 marks) c) Find the Thevenin s and Norton s equivalent circuits for the circuit shown in Figure Q2. (18 marks) Figure Q2
Page 4 of 7 Q3 A 50-Ω resistor, a 75-Ω inductive reactance, and a 100-Ω capacitive reactance are connected in series (Fig. Q3) across a typical UK AC power line of 230 V and 50 Hz. a) Draw the appropriate phasor diagram. b) Determine the values of: i. Total current Itot and total voltage Vtot. ii. Phase angle θ 0 between reference phasor and Itot or between reference phasor and Vtot. iii. Impedance Z. c) Determine if the circuit is inductive or capacitive and explain why. d) Calculate the resonant frequency of the RLC circuit. e) Calculate the peak current flowing in the circuit at the resonant frequency. Figure Q3: RLC circuit in series
Page 5 of 7 Q4 a) A full wave rectifier circuit converts an AC supply to a pulsed DC voltage. i) Draw the circuit for a full wave rectifier including a reservoir capacitor. ii) iii) Describe how the full wave rectifier circuit functions for each half cycle of the supply voltage. Sketch the waveforms showing the effect of adding a reservoir capacitor to the output of a full wave rectifier circuit. b) A stepper motor has an angular resolution of 2.5 degrees per step. If the clock input producing the stepper motor drive sequence is 100Hz, what will be the rotational speed of the stepper motor in revolutions per minute? (10 marks)
Page 6 of 7 Q5 a) Describe the basic elements in a Generalized Medical Instrumentation System. Illustrate your answer with the aid of diagrams. (9 marks) b) Compare the Thermocouple, Resistance Temperature Detectors (RTDs) and Integrated Circuit (IC) Temperature Sensors in term of cost, temperature, response and accuracy. (12 marks) c) Explain what micro shock in medical instrumentation is. Illustrate your answer with the aid of diagrams if necessary. (4 marks) END OF QUESTIONS for formula sheet
Page 7 of 7 Formula sheet The following symbols in the formulae have their standard meaning: Ohms Law: V IR Power: P IV Potential Divider: V R2 V 2 ( V1 V 2) R1 R2 Capacitance: Q CV NI Magnetic Field Strength: H l The Circumference of a Circle: l 2 r Angular Frequency: 2 f Magnitude of the Reactance of Inductor L: Magnitude of the Reactance of Capacitor C: X L L 1 X C C