A solenoid has a core of a material with relative permeability 400. The windings of the solenoid are insulated from the core and carry a current of 2 A. If the number of turns is 1000 per meter then the value of magnetic intensity will be .

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(1) 2 × 10³ Am⁻¹. Given: n=1000 turns per metre, I=2 A, core of relative permeability μᵣ=400. Idea: the magnetic intensity H is set by the free current in the winding alone -- it is the same with or without the core. For a long solenoid H=nI. H=1000×2=2×10³ A m⁻¹. The core's μᵣ shows up in the other two quantities, not in H: the magnetisation is M=(μᵣ-1)H=399×2×10³≈8×10⁵ A m⁻¹, and the field is B=μ₀(H+M)=μ₀μᵣH=1.0 T. So the magnetic intensity is 2×10³ A m⁻¹.

A solenoid has a core of a material with relative permeability 400. The windings of the solenoid are insulated from the core and carry a current of 2 A. If the number of turns is 1000 per meter then the value of magnetic intensity will be ________.

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