Suppose you have a pure DC supply with a constant current to an inductor. And you change the core of the inductor from air to iron, leaving the current remain the same. You may try changing to other materials. Does the voltage drop across the inductor will remain the same for any core? Anyone who performed an experiment on this? Or have an answer. Note, I am not referring to changing magnetic field. Voltage measurement should be done during the time the magnetic field becomes stable.