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Physics · Current Electricity

NEET (UG) 2023 — Question 43

The resistance of platinum wire at 0∘C0^{\circ} \mathrm{C} is 2Ω2 \Omega and 6.8Ω6.8 \Omega at 80∘C80^{\circ} \mathrm{C}. The temperature coefficient of resistance of the wire is :

  1. Option A:

    3×10−3∘C−13 \times 10^{-3}{ }^{\circ} \mathrm{C}^{-1}

  2. Option B:

    3×10−2∘C−13 \times 10^{-2}{ }^{\circ} \mathrm{C}^{-1}

    Correct
  3. Option C:

    3×10−1∘C−13 \times 10^{-1}{ }^{\circ} \mathrm{C}^{-1}

  4. Option D:

    3×10−4∘C−13 \times 10^{-4}{ }^{\circ} \mathrm{C}^{-1}

Answer: B

Step-by-step solution

Using R=R0(1+αΔT)R=R_0(1+\alpha \Delta T) where α\alpha is the thermal coefficient of resistance

6.8=2{1+α(80−0)}6.82−1=α×80α=3.4−180=2.480=0.03∴α=3×10−2∘C−1\begin{aligned} & 6.8=2\{1+\alpha(80-0)\} \\ & \frac{6.8}{2}-1=\alpha \times 80 \\ & \alpha=\frac{3.4-1}{80}=\frac{2.4}{80}=0.03 \\ & \therefore \alpha=3 \times 10^{-2}{ }^{\circ} \mathrm{C}^{-1} \end{aligned}

Answer key and solution verified before publishing.

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Exam
NEET (UG) 2023
Paper
2023 paper
Subject
Physics
Chapter
Current Electricity
Topic
Heating Effects of Current and Thermal Powe

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