A solenoid has a core of a material with relative permeability 400. The windings of solenoid are insulated from the core and carry a current of 2 A. If the number of turns is 1000 per meter, the magnetic field B inside the solenoid is T.

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Accepted Answer

(2) 1.0. Given: μᵣ=400, I=2 A, n=1000 turns per metre. Idea: the winding fixes the magnetic intensity H=nI; the core then responds, and the field inside is B=μ₀μᵣH. H=1000×2=2×10³ A m⁻¹. B=(4π×10⁻⁷)(400)(2×10³)=(4π×10⁻⁷)(8×10⁵) B=1.0 T to two figures. Without the core the same winding would give only μ₀H=2.5×10⁻³ T: the core multiplies the field 400 times, which is the whole point of using one. So B=1.0 T.

A solenoid has a core of a material with relative permeability 400. The windings of solenoid are insulated from the core and carry a current of 2 A. If the number of turns is 1000 per meter, the magnetic field B inside the solenoid is ______ T.

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