Question

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

• A. ${500}^{0}C$
• B. ${450}^{0}C$
• C. ${600}^{0}C$
• D. None of these

Answer 1

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

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 $500{}^{o}C$