The Electrical Properties Of Solids

When a conductor like copper is cooled, its resistance typically increases because the atomic vibrations decrease, leading to reduced mobility of the free electrons. For semiconductors like germanium, its resistance decreases as temperature decreases due to increased charge carrier mobility. Thus, as the temperature is reduced from room temperature to 100K: - The resistance of copper increases. - The resistance of germanium decreases. Thus, the correct option is (B).