03. Magnetic Field at the Centre of a Current Loop

The magnetic field at the centre of a circular current loop is axial. The equation for this is:

Bz = (mu0 x I)/(2 x R)

where the current in the loop is I and the radius of the loop is R.

This equation was used to calculate the amplitude of a magnetic field at the centre of a 10 cm radius loop with a current of 1 Ampere. Programs TB-FIELD.EXE and SF-FLD1.EXE were used to calculate axial magnetic field components near the centres of thin coils (radial position of calculation = 1E-10 m or 1 angstrom). For TB-FIELD.EXE, the tubes in the calculation was given the properties of free space (electrical conductivity = 0 and relative magnetic permeability = 1). For SF-FLD1.EXE, the plates were also given the properties of free space (electrical conductivity = 0 and relative magnetic permeability = 1).

Results of the comparisons between calculations by TB-FIELD.EXE and SF-FLD1.EXE with the theoretical result given by the equation above are listed in the table below:

The Input screen for TB-FIELD.EXE for the coil used to simulate the current loop is shown below: