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There is a coil of 100 turns having radius 10 cm and carrying a current of 1 A. The magnitude of magnetic field at the centre of the coil is ______ T.

Asked in GSEB Board July 2021 · Rotating charges and multiple loops

Answer: (1) 2π×10⁻⁴

Step-by-step solution

Given: N=100 turns, R=10 cm=0.1 m, I=1 A.

Idea: at the centre of a circular coil of N turns every element of the wire is the same distance R away and contributes in the same direction, giving B=(μ₀NI)/(2R).

B=(4π×10⁻⁷×100×1)/(2×0.1)

Top: 4π×10⁻⁵. Bottom: 0.2.

B=2π×10⁻⁴ T, which is about 6.3×10⁻⁴ T.

Why the other options are wrong

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