Solenoid Magnetic Field
Solenoid Magnetic Field
A long solenoid produces a nearly uniform field inside, set by its turn density and current — the workhorse electromagnet.
The field is B = μ_0·n·I. where μ_0 is the permeability of free space, n the turns per metre and I the current.
Inputs
mu_0 := 1.2566e-6 T·m/A=1.26e-06 kg·m/A^2/s^2
n := 2000 m^-1=2000 1/m
I := 3 A=3 A
Apply the long-solenoid field formula.
B := mu_0·n·I=7.54e-03 kg/A/s^2
Results
More turns per metre or more current strengthens the field. Inserting an iron core multiplies it by the core’s relative permeability.
Assumptions & limitations
- Long solenoid (length ≫ diameter).
- Air core.
- Field at the centre.