Question

At what change in temperature will the resistance of a copper wire become three times its value at $0^{0}C$? [Temperature coefficient of resistance for copper $4\times {10}^{-3}$]:-

• A. 400 ${}^{0}C$
• B. 450 ${}^{0}C$
• C. 500${}^{0}C$
• D. 60${}^{0}C$

Answer 1

The correct option is C 500${}^{0}C$

Given,

Resistance become $R=3R_o$

$R=R_0(1+\alpha \Delta T)$

$3R_o=R_o(1+\alpha \Delta T)$

$\Delta T=\frac{2}{\alpha }=\frac{2}{4\times {10}^{-3}}=500{}^{o}C$

Hence, when rise in temperature is $500{}^{o}C$