JAMB - Physics (1990 - No. 11)
The resistances of platinum wire at the ice and steam points are 0.75 ohm and 1.05 ohm respectively. Determine the temperature at which the resistance of the wire is 0.90 ohm
43.0oC
50.0oC
69.9oC
87.0oC
Explication
100oC .... 1.05\(\theta\)
\(\theta\)oC .... 0.9\(\theta\)
0oC .... 0.75\(\theta\)
\(\frac{\theta - 0}{100 - 0}\) = \(\frac{0.9 - 0.75}{1.05 - 0.75}\)
\(\theta\) = 50oC
\(\theta\)oC .... 0.9\(\theta\)
0oC .... 0.75\(\theta\)
\(\frac{\theta - 0}{100 - 0}\) = \(\frac{0.9 - 0.75}{1.05 - 0.75}\)
\(\theta\) = 50oC