The electrical resistance in ohms of a certain thermometer varies with temperature according to the approximate law : R = Ro[1 + α (T – To )] The resistance is 101.6 Ω at the triple-point of water 273.16 K, and 165.5 Ω at the normal melting point of lead (600.5 K). What is the temperature when the resistance is 123.4 Ω?
We first find α by putting the given values, 165.5=101.6(1+α(600.5−273.16)) ∴α=1.92×10−3 Now, Temp when Resistance is 123.4 is 123.4=101.6(1+α(T−273.16)) T=384.91 K
