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JEE Main 2026 (28 Jan, Shift 1) · Biot-Savart Law & Circular Coils

Biot-Savart Law & Circular Coils question from JEE Main 2026 (28 Jan, Shift 1)

Q4JEE Main 2026 · 28 JAN · SHIFT 1Easy

Biot-Savart Law & Circular Coils

The magnetic field at the centre of a current carrying circular loop of radius RR is 16 μT16\ \mu\text{T}. The magnetic field at a distance x=3Rx = \sqrt{3} R on its axis from the centre is

‾ μT\underline{\qquad}\ \mu\text{T}.

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Answer: (b)

  1. BxBc=R3(R2+x2)3/2\frac{B_x}{B_c} = \frac{R^3}{(R^2+x^2)^{3/2}}
  2. x=3R⇒(4R2)3/2=8R3x = \sqrt{3}R \Rightarrow (4R^2)^{3/2} = 8R^3, so Bx=Bc8=168B_x = \frac{B_c}{8} = \frac{16}{8}
  3. So the answer is (b) 2 μT2\ \mu\text{T}.
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