Question

Metallic conductors and semiconductors are heated separately. What are the changes in conductivity?

• A. Increase, Increase
• B. Decrease, Decrease
• C. Increase, Decrease
• D. Decrease, Increase

Answer 1

The Correct Option is D

Conductivity in materials depends on the availability of free charge carriers and their mobility.

1. For metallic conductors: Conductivity decreases with an increase in temperature. This is because as temperature rises, the lattice vibrations in the metal increase, leading to more frequent collisions between electrons and the lattice ions. This reduces the mobility of electrons, thereby decreasing conductivity.
2. For semiconductors: Conductivity increases with an increase in temperature. In semiconductors, thermal energy excites more electrons from the valence band to the conduction band, increasing the number of free charge carriers (electrons and holes). This leads to higher conductivity at elevated temperatures.

Thus, the correct answer is that the conductivity of metals decreases while the conductivity of semiconductors increases when heated.