Distance from the center of the coil.
Field (mT) · Axial distance (mm) · Shaded band = winding length
Electromagnet Explorer
Shape the coil. Explore its field.
Coil settings
Guided experiments
Try changing one setting at a time. Watch the model and results respond together.
3D model
AIR CORELoading the 3D workbench…
Drag to rotate · Scroll or pinch to zoom · Field lines are schematic
Live results
Air-core estimateField along the centerline View chart
How it works & model assumptions
How the coil works
A current-carrying coil creates a magnetic field. Its direction follows the right-hand rule: curl your fingers with the conventional current and your thumb points toward the north end. Reversing the current swaps the poles.
What the estimates mean
Air-core results sum circular-turn fields along the axis. The iron setting demonstrates enhancement and saturation using a simplified response. Neither the field illustration nor the iron chart is a solved three-dimensional field map. Power is heat generation in watts, not a predicted temperature or a continuous-duty rating.
Equations & references
For each turn: B(z) = μ₀ I r² / [2(r² + (z − z₀)²)3/2]. Sum over the turns. Copper R = ρℓ/A; voltage magnitude = |I|R; power = I²R. Iron illustration: B = Bair + 1.6 tanh(9Bair/1.6), in tesla.
Georgia State: solenoid fields · Ferromagnetism and saturation · Copper resistivity
The winding is drawn as circular turns with schematic connections; calculations include the small helical-pitch wire-length correction. The reference constant μ₀ ≈ 4π × 10⁻⁷ H/m is adequate for this learning model.
Model assumptions
Copper at 20°C. Insulation adds 0.05 mm to wire diameter. Close-packed layers; a partial final layer is centered. Leads and inter-layer connections are excluded from wire length and resistance.
Iron rod fills the bore and extends through the winding. Teaching model: effective low-field gain 10×; saturating added magnetization of 1.6 T. These are illustrative assumptions, not properties of a specified iron grade. No hysteresis, remanence, thermal feedback or AC effects.