The temperature dependence of resistance of Cu and undoped Si in the temperature range 300 - 400 K, is best described by: (a) Linear increases for Cu, exponential decrease of Si. (b) Linear decrease for Cu, linear decrease for Si (c) Linear increase for Cu, linear increase for Si. (d) Linear increase for Cu, exponential increase for Si

Answer: (a). Cu (metal): R = R₀(1 + α Δ T), a linear increase with temperature. Undoped Si: carrier density ∝ e-Eg/2kT, so resistance decreases exponentially with temperature. So the answer is (a) linear increase for Cu, exponential decrease for Si.

The temperature dependence of resistance of Cu and undoped Si in the… | JEE Main 2016

Q48JEE Main 2016Difficult

Intrinsic & Extrinsic Semiconductors

The temperature dependence of resistance of $\text{Cu}$ and undoped $\text{Si}$ in the temperature range $300 - 400\text{ K},$ is best described by:

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Answer: (a)

Cu (metal): $R = R_0(1 + \alpha \Delta T)$ , a linear increase with temperature.
Undoped Si: carrier density $\propto e^{-E_g/2kT}$ , so resistance decreases exponentially with temperature.
So the answer is (a) linear increase for Cu, exponential decrease for Si.

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