Here the magnetic field is of a
cylinderical form, centred on the centre of the current path. This path will
normally be through a conductor but needed not necessarily be so. The direction
of the field is given by the Right Hand Screw Rule.
When a current I (Amps) flows,
the flux density (B), at a distance of d metres from the centre of the current
path is given by;
the flux density (B), at a distance of d metres from the centre of the current
path is given by;
