V-I graph for a platinum wire at temperatures $T_1$ and $T_2$ is shown in the given figure. The temperature difference $(T_2-T_1)$ is proportional to:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → $\cot 2θ$
for a metal like platinum, the resistance is,
$R_T=R_0(1+α(T-T_0))$
and,
The temperature difference is proportional to the change in the slopes of the V-I graphs.
$T_2-T_1∝\tan(90-2θ)$
$∝\cot 2θ$