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JEE Main 2023 (29 Jan, Shift 1) · Magnetic Field of Straight Wires

Magnetic Field of Straight Wires question from JEE Main 2023 (29 Jan, Shift 1)

Q44JEE Main 2023 · 29 JAN · SHIFT 1Medium

Magnetic Field of Straight Wires

The magnitude of magnetic induction at mid point O\text{O} due to current arrangement as shown in Fig will be

Figure

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Answer: (a)

  1. AB and ED lie on the line through O, so they give zero field.
  2. BC and ET are semi-infinite wires starting at the foot of the perpendicular from O, each at distance a2\frac{a}{2}: B=μ0I4π(a/2)=μ0I2πaB = \frac{\mu_0 I}{4\pi (a/2)} = \frac{\mu_0 I}{2\pi a}.
  3. Both point out of the page, so they add: B=2×μ0I2πa=μ0IπaB = 2 \times \frac{\mu_0 I}{2\pi a} = \frac{\mu_0 I}{\pi a}
  4. So the answer is (a).
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