Question

EET3122 Quiz3 Name: 1. A DC Wheatstone bridge contains three resistors whose resistance values are constant at, and one component with unknown resistance value. Given V, (a) The output voltage Vo is measured to be 0 V. Determine the resistance of 3000 2.1 300012 AT (b) Suppose the unknown component is a temperature sensor. After temperature increases, the output voltage V, changes from 0 V to 6.2 mV. Determine the resistance of R(T).

Answer 1

IN Vo = Va- Vb 3001 33009 3002 600 ã = 1.35 V a) Given Vo = OV 3.1VT . R = ? . Va = 3.10 R 300+R Vo = 3.1 x 300 = 3-1 X300 = 3,= 1.55 V 300+300 Vo = Va-Vb=0 = Va = Vb 3.1 R = 1.55 300+R 3.1 R = 1.55 (300 + R} 3.1R = 465 +1.55R 3.1 R - 1.55 R = 465 1.55 R = 465 R=465 1:55 R = 300-2

b) Given, unknown component is a temperature Seneor and Ve = 6.2 V. Va - Vb = 6.2 3.18 -1.55 = 6.2 300+R 3.1R = 7.75 300 +R - 3.1R = 7.75 (300 +R) 3.1R = 2325+ 7.75R 7.75 R – 3.12 = -2325 465 R = -2325 R = 2325 = -50012 4.65 :: Temperature sensors has negative resukine Coefficient so the resistance valute cames to be negative,