In this section we are dealing with the self inductance of a single coil rather than the mutual inductance between two coils. If the current through a single coil changes, the magnetic field inside th...In this section we are dealing with the self inductance of a single coil rather than the mutual inductance between two coils. If the current through a single coil changes, the magnetic field inside that coil will change; consequently a back EMF will be induced in the coil that will oppose the change in the magnetic field and indeed will oppose the change of current.