Question

Consider two cuboidal blocks of volume 1 cm\(^3\) each, one made of gold and the other of undoped silicon. What will happen to the resistivity of these blocks if the temperature is increased from 300 K to 350 K?

• A. Resistivity of gold increases and undoped silicon decreases
• B. Resistivity of gold decreases and undoped silicon increases
• C. Resistivity of gold remains same and undoped silicon increases
• D. Resistivity of gold decreases and undoped silicon remains same

Hint:

For metals like gold, resistivity increases with temperature, while for semiconductors like silicon, resistivity decreases as the number of charge carriers increases.

Answer 1

The Correct Option is A

Step 1: Understanding the behavior of resistivity in gold (metal).
Gold is a metal, and in metals, the resistivity increases with temperature. This is due to the increased vibration of atoms at higher temperatures, which causes more collisions between the free electrons and atoms, making it harder for the electrons to move. Therefore, the resistivity of gold increases as the temperature increases. 
Step 2: Understanding the behavior of resistivity in undoped silicon (semiconductor). 
For semiconductors like undoped silicon, the resistivity decreases as the temperature increases. This is because, at higher temperatures, more electrons gain enough energy to jump from the valence band to the conduction band, increasing the number of charge carriers. As a result, the resistivity of undoped silicon decreases with an increase in temperature.