Question

The temperature coefficient of resistance of a wire at $0^{\circ} \,C$ is $0.00125^{\circ}\, C ^{-1}$. At $25^{\circ}\, C$ its resistance is one ohm. The resistance of the wire will be $1.2 \,ohm$ at

• A. $225\, K$
• B. $190^{\circ}\, C$
• C. $260^{\circ} \,C$
• D. $185 \,K$

Answer 1

Answer: (B)

$1=R_{0}(1+(0.00125)(25)) $
$1.2=R_{0}(1+(0.00125)\, \theta)$
$\frac{12}{10}=\frac{1+0.00125 \theta}{1.03125}$
Solving, we get
$\theta=190^{\circ} \,C$