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CUET · PHYSICS · PYQ PAPER 2023

A wire of resistance \( 5\Omega \) is drawn out so that its length is increased by thrice its original length. The new resistance would be :

  1. A \( 10 \Omega \)
  2. B \( 20 \Omega \)
  3. C \( 40 \Omega \)
  4. D \( 45 \Omega \)
Verified Solution

Answer & Solution

Correct Answer

(D) \( 45 \Omega \)

Step-by-step Solution

Detailed explanation

\(R \propto \frac{L^2}{V}\) or \(R \propto L^2\) (since volume \(V\) and resistivity \(\rho\) are constant). \(\frac{R_2}{R_1} = \left(\frac{L_2}{L_1}\right)^2\) \(L_2 = 3L_1\) \(\frac{R_2}{R_1} = \left(\frac{3L_1}{L_1}\right)^2 = 3^2 = 9\)…
From CUET
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