Q108 / 120 · VITEEE 2007 · Physics

The temperature coefficient of resistance of a wire is $0.00125 / \mathrm{K}$. At $300 \mathrm{~K}$ its resistance is $1 \Omega$. The resistance of the wire will be $2 \Omega$ at

  • A
    $1154 \mathrm{~K}$
  • Correct answer
    B
    $1100 \mathrm{~K}$
  • C
    $1400 \mathrm{~K}$
  • D
    $1127 \mathrm{~K}$

Solution

Temperature coefficient, $\alpha=\frac{R_{2}-R_{1}}{R_{1}\left(t_{2}-t_{1}\right)}$ $\Rightarrow\left(t_{2}-t_{1}\right)=\frac{R_{2}-R_{1}}{\alpha R_{1}}$ $\Rightarrow t_{2}-t_{1}=\frac{2-1}{1 \times 0.00125}$ $t_{2}=\frac{1}{0.00125}+t_{1}=800+300=1100 \mathrm{~K}$

Hence, the correct answer is option: 'B'.

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