Question

Problem 3 (25 pts.) A J-type thermocouple is calibrated against an RTD standard to within +0.02°C between 0° and 200°C. The emf is measured with an A/D converter having a resolution of 0.075 mV. The reference junction temperature is provided by an ice bath. The calibration procedure yields the following linear equation: T(°C) = 0.11 + 19.2V ,where the units of voltage Vis mV. This first order curve fit has an error of 0.5°C. Part a) 15 pts. Find the uncertainty in the temperature measurement within the range of temperature values. Part b) 10 pts. Suppose the ice bath has melted and the reference junction is now at room temperature of 25°C. What is the temperature sensed by the thermocouple if the emf at the measuring junction is 4 mV?

Answer 1

a) uncertainity is a range of values in which the true value lies. No measurement device is perfect. The accuracy for every measurement is limited. For example, white measuring length of a line, somme may read it as 11.22 mm While other 11.28 and third One 11.21 Now we can assurely say that value is 11.26 This x is nothing but incertainity, So, measured value should be expressed as 11.2d 10.01 Thus, rather meaning a fisted reading, we gef range of values in which the true value thes, The PID reading is 10.02% and claive fit has enor of Mare Possible enos a 10.02 +0.5 10.5% Thus when measuring this the mocouple as 506, the actual value will be 50 20.50 Thus, uncertainity is $0.52'c 6 Tz Ollt 19.00 i vzdemu = 0.002 V Ta 0.117692 x0.004) The thermocuple will sense a temperature of 0. 18680 Buy 0.5°C Am] (Part a =10.18680