As the temperature of a metal conductor rises, its resistance
- A. increases, because the lattice ions vibrate more and impede the electrons
- B. decreases, because the electrons move faster
- C. stays constant
- D. falls to zero
Explanation
More vigorous lattice vibrations scatter the drifting electrons more often, shortening the mean free path and raising resistance, which is why a filament lamp's resistance is much higher when lit. Semiconductors behave in the opposite way, since heating releases many more charge carriers and resistance drops sharply. That contrast is the basis of the thermistor.