Properties of Semiconductors: Practice Problem & Solution

Solution Explained:

To solve this problem, we apply the core principles of Properties of Semiconductors. Understanding the underlying formula is key to arriving at the correct answer below:

Copper is a metal (conductor), so its resistance decreases when cooled due to decreased lattice scattering. Germanium is a semiconductor, so its resistance increases when cooled because fewer charge carriers are thermally excited across the band gap.