NEET 2024 · PhysicsLoop centre fieldPrevious Year Question
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):
Answer: (B) 4.4 mT. Answer: (B) Solution: Field at centre of an N-turn circular coil: B = μ₀ N I / (2a).
- A.4.4 T
- B.4.4 mT✓
- C.44 T
- D.44 mT
Correct Answer
(B) 4.4 mT
Solution & Explanation
Answer: (B) Solution: Field at centre of an N-turn circular coil: B = μ₀ N I / (2a). N = 100, I = 7 A, a = 0.10 m. B = (4π × 10⁻⁷ × 100 × 7) / (2 × 0.10) B = (4π × 7 × 10⁻⁵) / 0.2 = 4π × 3.5 × 10⁻⁴ ≈ 4.4 × 10⁻³ T = 4.4 mT.
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