Question

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

• A. $3.456\,^{\circ}C$
• B. $34.565\,^{\circ}C$
• C. $345.65\,^{\circ}C$
• D. $45.65\,^{\circ}C$

Answer 1

Answer: (C)

$345.65\,^{\circ}C$

Answer 2

$R_{0}=5\,\Omega , R_{100}=5.23\, \Omega, R_{t}=5.795\,\Omega$ $\alpha=\frac{R_{100}-R_{0}}{R_{0}\times100}=\frac{R_{t}-R_{0}}{R_{0}\times t}$ $Therefore, t=\frac{R_{t}-R_{0}}{R_{100}-R_{0}}\times100$ $=\left(\frac{5.795-5}{5.23-5}\right)\times100$ $=345.65\,^{\circ} C$