When the coil is wrapped around a ferromagnetic core, why is it difficult to determine the inductance?
(a) The variation of flux is no longer proportional to the variation of current
(b) Current does not exist in the coil
(c) Flux does not exist in the coil
(d) The value of current is too large to measure
I had been asked this question in final exam.
My question is from Factors Determining the Inductance of a Coil in section Inductance in a DC Circuit of Basic Electrical Engineering