Question

The temperature coefficient of resistance of a wire is 0.00125 per K. At 300 K, its resistance is 1 ohm. At the resistance is 2 ohm.

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

Answer 1

The correct option is B 1100 K

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