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Question
A platinum resistance thermometer reads 0° when its resistance is 80 Ω and 100° when its resistance is 90 Ω.
Find the temperature at the platinum scale at which the resistance is 86 Ω.
Solution
Given:
Resistance at 0oC, R0 = 80
\[\Omega\]
Resistance at 100oC, R100 = 90
\[\Omega\]
Let t be the temperature at which the resistance (Rt) is 86
\[\Omega\]
\[t = \frac{R_t - R_0}{R_{100} - R_0} \times 100\]
\[ \Rightarrow t = \frac{86 - 80}{90 - 80} \times 100\]
\[ \Rightarrow t = \frac{6}{10} \times 100\]
\[ \Rightarrow t = 60°\]
Therefore, the resistance is 86
\[\Omega\] at 60°C
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