Property of a conductor , sometimes in the shape of a coil, that is measured by the size of the electromotive force (emf), or voltage, induced in it, compared with the rate of change of the electric current that produces the voltage.
A steadily changing electric current produces a varying magnetic field , which induces an emf in a conductor that is present in the field. The magnitude of this voltage is proportional to the rate of change of the current. The inductance is the proportionality factor. The unit of inductance is the henry, named after Joseph Henry ; one henry is equivalent to one volt divided by one ampere per second.