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CUET · PHYSICS · PYQ PAPER 2025

The external diameter of a 5 m long hollow copper tube is 10 cm and the thickness of its wall is 5 mm. If the specific resistance of copper be \( 1.7 \times 10^{-8} \, \Omega\text{-m} \), then its resistance would be approximately

  1. A \( 4.5 \times 10^{-5} \, \Omega \)
  2. B \( 6.0 \times 10^{-5} \, \Omega \)
  3. C \( 7.0 \times 10^{-5} \, \Omega \)
  4. D \( 8.0 \times 10^{-5} \, \Omega \)
Verified Solution

Answer & Solution

Correct Answer

(B) \( 6.0 \times 10^{-5} \, \Omega \)

Step-by-step Solution

Detailed explanation

\(R_{int} = (10 \text{ cm}/2) - 5 \text{ mm} = 0.05 \text{ m} - 0.005 \text{ m} = 0.045 \text{ m}\) \(A = \pi (R_{ext}^2 - R_{int}^2) = \pi ((0.05)^2 - (0.045)^2) = \pi (0.0025 - 0.002025) = \pi (0.000475) \text{ m}^2\)…
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