ME2143/ME2143E

Matriculation/Registration Number

NATIONAL UNIVERSITY OF SINGAPORE

ME2143/ME2143E SENSORS AND ACTUATORS (Semester I : AY2009-2010) Time Allowed: 2 Hours

___________________________________________________________________________EXAMINER'S USE ONLY

INSTRUCTIONS TO CANDIDATES:

Marking 1. This examination paper contains FOUR (4) questions and comprises EIGHTEEN (18) printed pages. Answer ALL FOUR (4) questions. All questions carry equal marks. You are to write on and submit this answer booklet only! This is a CLOSED-BOOK examination. QuestionInt. Ext. Ave.

2. 3. 4.

1 2 3 4

5.

6. You may bring in an A4-sized summary sheet. Total:

PAGE 2

ME2143/ME2143E

QUESTION 1 (25 marks) (a) Wheatstone bridge is often used in conjunction with an amplifier circuit as shown in Figure 1a. Each resistor of the Wheatstone bridge is a temperature-sensing element with nominal resistance Ro (=200). The change in resistance for each of these resistors is R = (T), where T is the temperature change, is a contant, and the sign is determined by the positive or negative temperature coefficient of the resistive element. (i) Find the Thvenin equivalent of the Wheatstone bridge that the amplifier sees at points a and b. Assume that |R|2