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A uniform wire of length l and radius r has a resistance of 100 Ω . It is recast into a wire of radius r 2 . The resistance of new wire will be-

Options

  1. A1600 Ω
  2. B100 Ω
  3. C200 Ω
  4. D400 Ω

Correct answer

A. 1600 Ω

Step-by-step solution

R = ρ l A A l = V R = ρ V A 2 ρ → constant V → constant R ∝ 1 A 2   ∝ 1 r 2 2 R ∝ 1 r 4 R 2 = 16 R 1 = 1600  Ω

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