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NEETPhysicsMagnetic Effects of Current

Two different experimental setups are used to levitate a straight horizontal wire using the magnetic force from a parallel fixed wire directly below it. In Setup 1, a free wire having mass per unit length ₁ carries a current I . It is levitated by a fixed wire carrying current I at a distance d below it. In Setup 2, a free wire having mass per unit length ₂ carries a current 2I . It is levitated by a fixed wire carry

Options

  1. A3 : 1
  2. B1 : 3
  3. C1 : 6
  4. D2 : 3

Correct answer

B. 1 : 3

Step-by-step solution

For a wire to be levitated, the upward magnetic force per unit length must balance its downward weight per unit length. In Setup 1: ₁ g = ₀ I I 2 d = ₀ I^2 2 d In Setup 2: ₂ g = ₀ (2I)(3I) 2 (2d) = 6 ₀ I^2 4 d = 3 ₀ I^2 2 d Dividing the equation for Setup 1 by the equation for Setup 2: ₁ g ₂ g = ₀ I^2 2 d 3 ₀ I^2 2 d ₁ ₂ = 1 3 Answer: 1 : 3

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