MAGNET FORMULAS

A small web site devoted to the vanishing art of practical magnet design without FEA (Finite Element Analysis).

The Basics    Maxwell and His Equations
The Law of Biot Savart
Mysterious Units of Magnetics
     
Simple Magnetic Field

Formulas

  Field due to electric current in an infinitely long, straight wire
Field inside an infinitely long, straight, air core solenoid
Field inside an air core toroid
Field due to a current loop
On-axis fields due to round, finite, air core solenoid shells
On-axis fields due to round, finite, air core solenoids
Off-axis field due to a current loop
  Off-axis fields due to a magnetic dipole moment
  Off-axis fields due to round, finite, air core solenoids
     
Helmholtz Coils for

High Field Uniformity

 

 

On-axis field due to two coaxial current loops with Helmholtz spacing
On-axis field due to two round, coaxial, finite solenoids with arbitrary or Helmholtz spacing
Off-axis fields due to two or more round, coaxial, finite solenoids with arbitrary spacing
     
Design Considerations Scaling rules
Coil cooling techniques and other rules of thumb
   

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