RE-NEET 2026 Physics Temperature Dependence of Resistance MCQ Question

In circuit (A), the resistors have a positive temperature coefficient (+α), meaning their resistance increases with temperature. Thus, as temperature rises, the resistance becomes $R_A = R_0(1 + \alpha \Delta T)$. According to Ohm's law, the current $I_A$ is given by:

$I_A = \frac{V}{R_A} = \frac{V}{R_0(1 + \alpha \Delta T)}$

As $\Delta T$ increases, $I_A$ decreases.

In circuit (B), the resistors have a negative temperature coefficient (−α), so their resistance decreases with temperature, leading to:

$R_B = R_0(1 - \alpha \Delta T)$

Thus, the current $I_B$ is:

$I_B = \frac{V}{R_B} = \frac{V}{R_0(1 - \alpha \Delta T)}$

As $\Delta T$ increases, $I_B$ increases.

Option D is correct because $I_A$ decreases while $I_B$ increases. The other options fail to accurately reflect the behavior of the currents based on the temperature coefficients.