Which of the following statements is correct? As the temperature increases:
- AThe resistivity of a semiconductor increases, whereas the resistivity of a conductor decreases
- BThe resistivity of a semiconductor decreases, whereas the resistivity of a conductor increases
- CThe resistivity of both a semiconductor and a conductor decreases
- DThe resistivity of both a semiconductor and a conductor increases
Show answer and explanation
Correct answer: (b) The resistivity of a semiconductor decreases, whereas the resistivity of a conductor increases
Explanation
As temperature rises:
- in a conductor (such as copper), the atoms vibrate more and the free electrons collide with them more often, so resistivity increases;
- in a semiconductor (such as silicon or germanium), more electrons gain enough energy to become free charge carriers, so resistivity decreases.
So conductors have a positive and semiconductors a negative temperature coefficient of resistance.