(a) Suppose that the variables shown in Fig. 6.2 have the following values:
R1 ¼ 100 U, R2 ¼ 100 U, R3 ¼ 100 U; and Vi ¼ 12V. Ru is a resistance thermometer with a resistance of 100 U at 100C and a temperature coefficient
of þ0.3 U/
C over the temperature range from 50C to 150C (i.e., the resistance increases as the temperature goes up). Draw a graph of bridge output
voltage V0 for 10C steps in temperature between 100C and 150C (calculating V0 according to Eq. 6.3).
(b) Briefly discuss whether you expect the graph that you have just drawn to be a
straight line.
(c) Draw a graph of V0 for similar temperature values if R2 ¼ R3 ¼ 1000 U and all
other components have the same values as given in part (a) above. Notice that
the line through the data points is straighter than that drawn in part (a) but the
output voltage is much less at each temperature point.
(d) Briefly discuss the change in linearity of the graph drawn for part (c) and the
change in measurement sensitivity compared with the graph drawn for part (a).