Determine the platinum wire at t 20 degrees Celsius, p = 20 Ohm, and at 500 degrees Celsius, p = 590 Ohm. Find alpha?

| April 11, 2021 | education

To find out the temperature coefficient of electrical resistance of platinum, we use the formula: Rheat = R0 * (1 + α * (Tload – T0)), from where we express: α * (Tload – T0) = Rheat / R0 – 1 and α = (Rheat / R0 – 1) / (Tload – T0).

Data: Rload – resistance in a heated state (Rload = 590 Ohm); R0 – initial resistance (R0 = 20 Ohm); Theat is the temperature of the heated platinum wire (Theat = 500 ºС); T0 – initial temperature (T0 = 20 ºС).

Let’s calculate: α = (Rload / R0 – 1) / (Tload – T0) = (590/20 – 1) / (500 – 20) = 0.059375 ºС-1.

Answer: The coefficient of electrical resistance of platinum, according to the calculation, is equal to 0.059375 ºС-1 (* tabular value α = 0.003729 ºС-1; in the condition there is inaccuracy: too high resistance in a heated state).



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