Lewhite, not sure that I understand the question, but the group delay behavior of an inductor will depend on both the amount of inductance and the design of the circuit that it is part of. Whether the inductor has an air core or a ferromagnetic core is not in itself relevant to that, although the two types may deviate from the behavior of an ideal inductor in ways that differ.
Also, current (I) lags voltage (E) for an inductor, not vice versa.
Regards,
-- Al
Also, current (I) lags voltage (E) for an inductor, not vice versa.
Regards,
-- Al