The resistance of the platinum wire of a platinum resistance thermometer at the ice point is 5 Ω and at the steam point is 5.23 Ω. When the thermometer is inserted in a hot bath, the resistance of the platinum wire is 5.795 Ω. Calculate the temperature of the bath.

Question

Accepted Answer

(1) 345.65 °C. Given: R₀=5 Ω at 0 °C, R₁₀₀=5.23 Ω at 100 °C, and Rₜ=5.795 Ω in the bath. Idea: the thermometer takes the resistance to rise linearly with temperature between the fixed points, Rₜ=R₀(1+α t). The rise is 5.23-5=0.23 Ω per 100 °C, that is 0.0023 Ω per degree. t=(Rₜ-R₀)/(R₁₀₀-R₀)×100=(0.795)/(0.23)×100. t=345.65 °C.

The resistance of the platinum wire of a platinum resistance thermometer at the ice point is 5 Ω and at the steam point is 5.23 Ω. When the thermometer is inserted in a hot bath, the resistance of the platinum wire is 5.795 Ω. Calculate the temperature of the bath.

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