The temperature coefficient of a resistance wire is 0.00125 per degree. The resistance at 300 K is 1 ohm. At what temperature its resistance will be 2 ohm ?
Answer & explanation
Correct answer: option 2
Temperature, t = 300 K = 27° C
$\mathrm{R}_{27}=1=\mathrm{R}_0(1+0.00125 \times 27)$
$\mathrm{R}_{\mathrm{t}}=2=\mathrm{R}_0(1+0.00125 \times \mathrm{t})$
∴ $\frac{2}{1}=\frac{1+0.00125 \times \mathrm{t}}{1+0.00125 \times 27}$
On solving, t = 854°C = 854 + 273 = 1127 K