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JEE Main 2026 (21 Jan, Shift 2) · Magnetic Field of Straight Wires

Magnetic Field of Straight Wires question from JEE Main 2026 (21 Jan, Shift 2)

Q13JEE Main 2026 · 21 JAN · SHIFT 2Medium

Magnetic Field of Straight Wires

An infinitely long straight wire carrying current II is bent in a planar shape as shown in the diagram. The radius of the circular part is rr. The magnetic field at the centre OO of the circular loop is:

Figure

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Answer: (b)

  1. Circular loop (current clockwise as seen from +x+x): μ0I2r\frac{\mu_0 I}{2r} along −i^-\hat{i}.
  2. Infinite straight wire ABDE at distance rr below O, current along +j^+\hat{j}: μ0I2πr\frac{\mu_0 I}{2\pi r} along +i^+\hat{i}.
  3. B⃗=−μ0I2πr(π−1)i^\vec{B} = -\frac{\mu_0 I}{2\pi r}(\pi - 1)\hat{i}
  4. So the answer is (b).
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