Question

The temperature coefficient of resistance of a wire is 0.00125 per °C. At 300 K, its resistance is 1 ohm. This resistance of the wire will be 2 ohm at
(IIT-JEE 1980)

• A. 1154°K
• B. 1100°K
• C. 1400°K
• D. 1127°K

Answer 1

The correct option is B 1100°K

Given,
At 300K,
$R_1=1\Omega$
$R_2$ = 2Ω at some T
∝ = 0.00125 $°C^{-1}$
$\frac{△R}{△}=\propto △T$
So $R_2=R_1(1+\propto △T)$
2 = 1( 1 + 0.00125 $△$ T)
$△T=\frac{1}{0.00125}$
= 800
$\therefore T_2=T_1+800$
= 300 + 800
$T_2=1100K$