PhysicsNEET 2022Biot–Savart and Ampère's laws

Moving Charges and Magnetism

A long solenoid of radius 1 mm has 100 turns per mm. If 1 A current flows in the solenoid, the magnetic field strength at the centre of the solenoid is:

A. $6.28 \times 1 0^{- 4}$ T
B. $6.28 \times 1 0^{- 2}$ T
C. $12.56 \times 1 0^{- 2}$ T✓
D. $12.56 \times 1 0^{- 4}$ T

You have the answer. The worked solution — and why the other three were written — is part of a paid pack.

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From Physics › Moving Charges and Magnetism › Biot–Savart and Ampère's laws — lectures, notes and every past question on it.

Last revised 7 Sept 2026. Found a mistake? Tell us — corrections are the fastest thing we act on.

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