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The resistance of platinum wire at $0^\circ C$ is $2\ \Omega$ and $6.8\ \Omega$ at $80^\circ C$. The temperature coefficient of resistance of the wire is:
Explanation
$R=R_0(1+\alpha\Delta T)$ gives $\alpha=3\times10^{-2}\ ^\circ C^{-1}$.
Detailed Solution
$R=R_0(1+\alpha\Delta T)$
$\Rightarrow6.8=2[1+\alpha\times(80-0)]$
$\Rightarrow\alpha=\frac{3.4-1}{80}=0.03$
$=3\times10^{-2}\ ^\circ C^{-1}$