Question

A wire has a resistance of $2.5$ $\Omega$ at $28$ ${}^{o}C$ and a resistance of $2.9$ $\Omega$ at $100$ ${}^{o}C$. The temperature coefficient of resistivity of material of the wire is?

• A. $1.06\times {10}^{-3}$ ${}^o{C}^{-1}$
• B. $3.5\times {10}^{-2}$ ${}^o{C}^{-1}$
• C. $2.22\times {10}^{-3}$ ${}^o{C}^{-1}$
• D. $3.95\times {10}^{-2}$ ${}^o{C}^{-1}$

Answer 1

Answer: (C)

$2.22\times {10}^{-3}$ ${}^o{C}^{-1}$

$R_{{28}^{o}c}=2.5$

$R_{{100}^{o}c}=2.9$

$\Delta R=\alpha \theta R_{{28}^{o}c}2.9-2.5=\alpha \times (100-28)\times 2.5\alpha =2.22\times {10}^{-3}°C$