# What is the inverse of the inductance?

That's for a homework. I'm asking what is 1/L, where L is inductance? I mean, as the inverse of the resistance is conductance, what is the inverse of the inductance.

• Can you figure it out yourself by looking up the definition of the unit Henry? Aug 24, 2012 at 12:22
• Are you sure you mean a true mathematical inverse, as in 1/H, or maybe the question is about a electrical component that is sortof a mirror image of a inductor with maybe voltage and current flipped? Aug 24, 2012 at 13:21
• Ohhh absolutely, i mean both electrical and mathematical meaning Aug 24, 2012 at 14:09
• I have never heard of an electrical concept related to the inverse of inductance, but an engineer/researcher (one that I've never heard of before) named Dewey Larson apparently proposed a system in which ALL quantities have inverses! He includes inductance, the inverse of which his paper labels as "reluctance, s3/t3, the resistance of a magnetic circuit to the establishment of a magnetic flux by a magnetomotive force" Aug 24, 2012 at 16:27
• I have an idea, but I'm reluctant to reveal it. Aug 24, 2012 at 16:50

## 1 Answer

Short answer: no such term exists. Susceptance is the reciprocal of reactance (good for pure inductors and capacitors) and admittance is the reciprocal of impedance (totally general), and that's as close as you'll get.

The unit Ohm for resistance is independent of frequency; it is just the ratio of voltage to current. For the purely reactive components, the component's physical value is more than that ratio - frequency is involved. "2πfL" appears as that ratio, the reactance and it's fine to have jargon for its reciprocal so we do our business with series and parallel circuits. We must deal with voltages and currents, Kirchoff's laws and all that, so all this is good.

Even part of that expression "2πf", the angular frequency (radians per second) has its reciprocal, the angular period (seconds per radian, not often used in real life) but alas, poor L the only actual physical constant in the inductor's equation has no defined terminology or unit for its reciprocal. It wouldn't be useful by itself.

However, I wouldn't be surprised if someone digging around in a university library for old, old electrical engineering and physics papers from the mid to late 19th Century, turns up some forgotten one-hit wonder that quickly faded into the mists of never-caught-on.

• Isn't magnetic reluctance defined as the inverse Henry (1/H)? Aug 23, 2015 at 0:58
• @ScottLawson: Yes, the units are reciprocal, but that does not necessarily mean the quantities themselves are. Magnetic reluctance is used for a different purpose: within magnetic circuits. In the cgs system of units, the yrneh is defined as the reciprocal of a henry. It is however not recognised by the SI system and is just a unit, which doesn't necessarily come with a quantity. An analogy: 1 siemens is the reciprocal of 1 ohm, but that does not make conductance the reciprocal quantity of reactance. However, it is the reciprocal of resistance which is measured in the same units as reactance. Dec 3, 2018 at 15:05