Question

The temperature coefficient of resistance of a wire of $ 0.00125/^{\circ} C $ . At $300 \,K$, its resistance is $1 \, \Omega $ . The resistance of the wire will be $2 \, \Omega $ , at following temperature

• A. 1127 K
• B. 1128 K
• C. 600 K
• D. 1400 K

Answer 1

Answer: (A)

According to definition of thermal resistance coefficient
$ \alpha =\frac{R_{2}-R_{1}}{R_{1}t_{2}-R_{2}t_{1}} $
$ 0.00125=\frac{2-1}{1\times t_{2}-2\times 27^{\circ}} $
$ 0.00125=\frac{1}{t_{2} 2 - 54^{\circ}} $
or $ t_{2}=854^{\circ}C $
Hence, $t_{2}=854+273$
$=1127\,K $