Solenoid Magnetic Field Calculator
Calculate ideal internal magnetic field and turn density for a long current-carrying solenoid.
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Estimate the internal field of a long solenoid
Enter total turns, coil length, signed current and relative permeability. The calculator derives turns per meter and reports the ideal internal magnetic field in teslas and milliteslas. Showing turn density beside the field clarifies why adding turns without changing length differs from stretching the same winding over a longer coil, while the current sign preserves a direction reference.
Check core and end behavior separately
The long-solenoid approximation treats the interior field as uniform and ignores winding thickness and ends. Real magnetic cores can saturate, exhibit hysteresis, heat and leak flux, while permeability may change strongly with field and frequency. Use a magnetic-circuit or field model with measured material curves when selecting a core, estimating force, controlling an actuator or setting safe current.
Frequently asked questions
Why does coil length affect the result?
The ideal field depends on turns per unit length, not total turns alone.
Can relative permeability stay constant?
Only as an approximation; real magnetic cores can be nonlinear and frequency dependent.
Is the field uniform near the coil ends?
No. End effects make the field weaker and less uniform there.