A tightly wound 100 turns coil of radius 10 cm carries a current of 7 A. The magnitude of the magnetic field at the centre of the coil is (Take permeability of free space as 4π×10^-7 SI units):

1. 44 T

2. 44 mT

3. 4.4 T

4. 4.4 mT

Doubtly Asked 30 Oct 2026 NEET UG 2024 Practice test neet Save WhatsApp Report

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Answer: 4. 4.4 mT

Key idea: Field at the centre of a circular coil of \(N\) turns: \(B=\frac{\mu_0NI}{2R}\).

\(B=\frac{4\pi\times10^{-7}\times100\times7}{2\times0.1}=\frac{8.8\times10^{-4}}{0.2}\approx4.4\times10^{-3}\) T \(=4.4\) mT.

Option 4.

Doubtly AI · 30 Oct 2026 AI-generated · not yet verified Report

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