Q125 / 180 · COMEDK 2026 (9 May Shift 2) · Physics
The voltage – current graph for a metal wire of uniform area of cross section at two different temp T and T' is shown. Then choose the correct statement:
- Correct answerATemperature T' is greater than temperature T
- BResistance of the conductor at temperature T is greater than resistance of the conductor at temperature T'
- CResistivity is independent of temperature
- DTemperature T is greater than temperature T'
Solution
From Ohm's law, $V = IR$, which gives $R = \dfrac{V}{I}$.
The given graph is an $I-V$ plot. The slope of this graph is $\dfrac{I}{V} = \dfrac{1}{R}$.
From the graph, for a given voltage $V$, the current $I$ at temperature $T$ is greater than the current $I'$ at temperature $T'$ ($I > I'$).
Therefore, the slope of the line for $T$ is greater than the slope of the line for $T'$.
This implies $\dfrac{1}{R_T} > \dfrac{1}{R_{T'}}$, which means $R_T < R_{T'}$.
For a metal wire, resistance increases with an increase in temperature. Since the resistance at $T'$ is greater than the resistance at $T$, the temperature $T'$ must be greater than $T$ ($T' > T$).
Answer: Temperature T' is greater than temperature T
The given graph is an $I-V$ plot. The slope of this graph is $\dfrac{I}{V} = \dfrac{1}{R}$.
From the graph, for a given voltage $V$, the current $I$ at temperature $T$ is greater than the current $I'$ at temperature $T'$ ($I > I'$).
Therefore, the slope of the line for $T$ is greater than the slope of the line for $T'$.
This implies $\dfrac{1}{R_T} > \dfrac{1}{R_{T'}}$, which means $R_T < R_{T'}$.
For a metal wire, resistance increases with an increase in temperature. Since the resistance at $T'$ is greater than the resistance at $T$, the temperature $T'$ must be greater than $T$ ($T' > T$).
Answer: Temperature T' is greater than temperature T
Hence, the correct answer is option: 'A'.