Question

Copper and silicon is cooled from 300 K to 60 K, the specific resistance

• A. decrease in copper but increase in silicon
• B. increase in copper but decrease in silicon
• C. increase in both
• D. decrease in both.

Answer 1

Answer: (A)

decrease in copper but increase in silicon

Answer 2

The specific resistance or resistivity , $?=?_0 (1+aT)$
where $a=$ temperature coefficient of resistivity is positive for metals (copper) and is negative for semiconductor ( silicon). Thus, when cooling , resistivity decreases in copper and increases in silicon.