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CUET · PHYSICS · PYQ PAPER 2025

A wire has a resistance of \( 3.0 \Omega \) at \( 30^{\circ}C \) and a resistance of \( 4.5 \Omega \) at \( 100^{\circ}C \). The temperature coefficient of resistance of the wire is

  1. A \( 0.0032 \text{ }^{\circ}C^{-1} \)
  2. B \( 0.0071 \text{ }^{\circ}C^{-1} \)
  3. C \( 0.012 \text{ }^{\circ}C^{-1} \)
  4. D \( 0.126 \text{ }^{\circ}C^{-1} \)
Verified Solution

Answer & Solution

Correct Answer

(B) \( 0.0071 \text{ }^{\circ}C^{-1} \)

Step-by-step Solution

Detailed explanation

\( \alpha = \frac{R_2 - R_1}{R_1 (T_2 - T_1)} \) \( \alpha = \frac{4.5 - 3.0}{3.0 (100 - 30)} = \frac{1.5}{3.0 \times 70} = \frac{1.5}{210} \) \( \alpha = 0.0071 \, ^{\circ}C^{-1} \)