A piece of silver and another of silicon are cooled from 15 °C to 3 °C. What will be the effect on resistance of each?

Silver: decreases; Silicon : increases

The correct answer is Option (2) → Silver: decreases; Silicon : increases

Resistance of a material: $R = R_0(1 + \alpha \Delta T)$

For silver (metal): $\alpha_\text{Ag} > 0$, so lowering temperature decreases resistance.

For silicon (semiconductor): conductivity increases as temperature decreases, so $\alpha_\text{Si} < 0$, resistance increases as temperature decreases.

Effect:

- Silver: resistance decreases

- Silicon: resistance increases