Question

(i) Let the resistance R of a piece of wire be a thermometric property for measuring the temperature T. Assume that where a and b are constants. The resistance of the wire is found to be 512 when it is at the temperature of melting ice and 70 when it is at the temperature at which water boils at atmospheric pressure. If the ice point is taken as 100° and the boiling point as 5000 on a particular scale, what is the temperature on this scale when R 5.5 Ω? ii) A thermocouple consists of two wires made of dissimilar metals that are joined together to form an electrical circuit. A theremal electromotive force (emf) 8 is generated when the two junctions are at different temperatures point and the other at a Celsius temperature T, the thermometric function is given by . When one junction is held at the ice where E is in millivolts. Calculate the constants a and b for a thermocouple reading 60 mV at 200°C and 40 mV at 400°C (iii) Consider the linear relationship between the thermometric property X and the temper- ature T given by Suppose that the ice (i) point and the steam (s) point are used as fixed points with temperatures of 0° and 100°, respectively. Show that X - Xi X,-X, T= 100 (iv) Show that if, instead, the thermometric function is chosen as then on the new scale In(X/Xi) In(X,/Xi) T 100

Answer 1