Pieces of copper and of silicon are initially at room temperature. Both are heated to temperature T. The conductivity of
- (A)both increases
- (B)both decreases
- (C)copper increases but silicon decreases
- (D)copper decreases but silicon increases✓ Correct
Answer: (D)
Solution
Copper is a metal: its number of free electrons is essentially fixed, but heating increases lattice vibrations and carrier scattering, so its resistivity rises and its conductivity decreases.
Silicon is a semiconductor: heating breaks more covalent bonds and generates many extra electron-hole pairs, so its conductivity increases.
Hence the conductivity of copper decreases while that of silicon increases.
Silicon is a semiconductor: heating breaks more covalent bonds and generates many extra electron-hole pairs, so its conductivity increases.
Hence the conductivity of copper decreases while that of silicon increases.
CBSE Class 12 Board · 2023 · Single correct option