Question

The resistance of a copper wire and an iron wire at 20C are 4.$\Omega$ and 3.9$\Omega$ respectively. Neglecting any thermal expansion, find the temperature at which resistances of bolh are equal.
${\alpha }_{cu}=4.0\times {10}^{-3}{K}^{-1}$. and ${\alpha }_{fe}=4.0\times {10}^{-3}{K}^{-1}$.

• A. ${65}^{o}C$
• B. ${75}^{o}C$
• C. ${270}^{o}C$
• D. ${95}^{o}C$

Answer 1

The correct option is C ${270}^{o}C$