Estimate coil field, spacing, and heating instantly. Review exact values, ideal values, units, and conversions. Useful for lab setups needing stable magnetic field control.
Exact field uses the two-coil center-field equation for identical circular coils. Ideal field assumes classic Helmholtz spacing where separation equals coil radius.
For the most uniform central field, use spacing equal to radius. Leaving relative permeability at 1 suits air-core laboratory coils.
| Turns | Current (A) | Radius (m) | Spacing (m) | Relative Permeability | Exact Center Field (mT) |
|---|---|---|---|---|---|
| 100 | 1.50 | 0.10 | 0.10 | 1.00 | 1.349 |
| 150 | 2.50 | 0.12 | 0.12 | 1.00 | 2.518 |
| 200 | 3.00 | 0.15 | 0.15 | 1.00 | 3.595 |
Exact center field for two identical circular coils:
B = μ0 × μr × N × I × R² / (R² + (s/2)²)^(3/2)
Ideal Helmholtz field when spacing equals radius:
BH = (4/5)^(3/2) × μ0 × μr × N × I / R
Electrical estimates:
V = I × Rcoil, and P = I² × Rcoil
Here, μ0 is the permeability of free space, μr is relative permeability, N is turns per coil, I is current, R is coil radius, and s is center-to-center spacing between the two coils.
It generates a nearly uniform magnetic field near the midpoint between two identical circular coils. This is useful for calibration, sensor testing, and controlled magnetic experiments.
That spacing minimizes field curvature near the center. It creates the classic Helmholtz condition, improving uniformity across a small central working volume.
The displayed exact center field is exact for the midpoint on the common axis of two identical circular coils. It does not map off-axis field variations.
Use values above 1 only when the field region contains magnetic material that changes permeability. Standard air-core laboratory coils usually use 1.
One tesla equals 10,000 gauss. Small laboratory coil fields are often reported in millitesla, microtesla, or gauss for convenience.
They help estimate supply requirements and thermal load. Higher current increases field strength, but it also raises heating and operating cost.
Yes. If you enter a target field, it estimates the current needed using the exact center-field model for your chosen geometry and permeability.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.