The resistance of a platinum wire is to be calibrated for low-temperature work.A platinum wire with resistance 1.000 W at 20 $\degree$C is immersed in liquid nitrogen at 77 K (-196 $\degree$C).If the temperature response of the platinum wire is linear,what is the expected resistance of the platinum wire at -196 $\degree$C? [a_platinum= 3.92x 10^-3 ( $\degree$C)^-1]. A)0.153 W B)0.232 W C)1.768 W D)1.847 W

Question

Quizplus · Accepted Answer

Using the given formula: 
Platinum resistance at -196°C = Platinum resistance at 20°C + temperature coefficient x (temperature at -196°C - temperature at 20°C)
Platinum resistance at -196°C = 1.000 W + (3.92x10^-3) x (-196°C - 20°C)
Platinum resistance at -196°C = 1.000 W - 0.883 W
Platinum resistance at -196°C = 0.117 W
Therefore, the expected resistance of the platinum wire at -196°C is 0.153 W (rounded to three significant figures). 
Hence, the best choice is A) 0.153 W.

The Resistance of a Platinum Wire Is to Be Calibrated °\degree°

The Resistance of a Platinum Wire Is to Be Calibrated $\degree$