Question

With increase in temperature, the resistivity of

• A. both Cu and Ge increases
• B. both nichrome and Ge decreases
• C. nichrome decreases and that of Ge increases
• D. both Cu and nichrome increases
• E. Cu, nichrome and Ge increases

Hint:

Physics Tip: Remember rule — Metals oppose more when hot, semiconductors conduct better when hot.

Answer 1

The Correct Option is D

Concept:
Different materials respond differently to temperature: - Metals: resistivity increases with temperature. - Alloys (nichrome): resistivity also increases slightly. - Semiconductors (Ge): resistivity decreases with temperature.
Step 1: Check Copper (Cu).
Copper is a metal. Hence resistivity increases with rise in temperature.
Step 2: Check Nichrome.
Nichrome is an alloy used in heaters. Its resistivity also increases with temperature.
Step 3: Check Germanium (Ge).
Germanium is a semiconductor. Number of free charge carriers increases with temperature, so resistivity decreases.
Thus only Cu and nichrome increase. Therefore correct option is (D). :contentReference[oaicite:1]{index=1}