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JEE Main202621 January 2026Evening ShiftPhysicsMagnetic Effects of CurrentActual

An infinitely long straight wire carrying current I is bent in a planer shape as shown in the diagram. The radius of the circular part is r . The magnetic field at the centre O of the circular loop is :

Options

  1. A- ₀ 2 I r ( -1) i
  2. B₀ 2 I r ( -1) i
  3. C- ₀ 2 I r ( +1) i
  4. D₀ 2 I r ( +1) i

Correct answer

A. - ₀ 2 I r ( -1) i

Step-by-step solution

B ₀= B _ AB + B _ DE + B _ BCD = ₀ i 4 r i + ₀ i 4 r i - ₀ i 2 r i = ₀ i 2 r i - ₀ i 2 r i = ₀ i 2 r (1- ) i =- ₀ i 2 r ( -1) i

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