Magnetic Force Between Magnets: Formula, Factors & Limitations

The force between two magnets depends on geometry, magnetization, and separation. For simple configurations (e.g., coaxial cylindrical magnets), an approximate formula is:

F = (B² × A) / (2μ₀)

• F = force (Newtons)
• B = magnetic flux density (Tesla) at the gap
• A = pole face area (m²)
• μ₀ = vacuum permeability (4π × 10⁻⁷ H/m)

Limitations: This assumes uniform field, infinite permeability, no fringing. Real magnets require finite element analysis (FEA) or experimental measurement. Force drops sharply with distance (~1/d⁴ for dipoles).