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The relationship Pt = P0(1 + αt) describes how resistivity changes with temperature. Copper's resistivity reduces as the temperature drops, while silicon's resistivity rises as the temperature decreases.

1. Copper's resistivity decreases as the temperature increases.
2. Copper's resistivity increases as the temperature decreases.
3. Silicon's resistivity decreases as the temperature increases.
4. Silicon's resistivity increases as the temperature decreases.

Correct answer: Silicon's resistivity increases as the temperature decreases.

Solution

For metals like copper, resistivity increases with temperature due to increased lattice vibrations. For semiconductors like silicon, resistivity decreases with increasing temperature as more charge carriers are generated. Thus, resistivity of Si increases with decrease in temperature.

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