inductance

inductance, quantity that measures the electromagnetic induction of an electric circuit component; it is a property of the component itself rather than of the circuit as a whole. The self-inductance, L, of a circuit component determines the magnitude of the electromagnetic force (emf) induced in it as a result of a given rate of change of the current through the component. Similarly, the mutual inductance, M, of two components, one in each of two separate but closely located circuits, determines the emf that each may induce in the other for a given current change. Inductance is expressed in henrys [for Joseph Henry]. An inductor is a device designed to produce an inductance, e.g., a coil; an ideal inductor, i.e., one having no resistance or capacitance (see impedance), is often called an inductance.

---

inductance

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.

---

inductance

The magnetic field that is generated when a current is passed through an inductor, typically a wire coil. Inductance is measured in henrys (H). See inductor and induction.

---

inductance

1. the property of an electric circuit as a result of which an electromotive force is created by a change of current in the same circuit (see self-inductance) or in a neighbouring circuit (see mutual inductance). It is usually measured in henries.

2. another name for inductor

---

inductance [in′dək·təns]

(electromagnetism)

That property of an electric circuit or of two neighboring circuits whereby an electromotive force is generated (by the process of electromagnetic induction) in one circuit by a change of current in itself or in the other.

Quantitatively, the ratio of the emf (electromotive force) to the rate of change of the current.

(control systems)

coil

---

Inductance

That property of an electric circuit or of two neighboring circuits whereby an electromotive force is induced (by the process of electromagnetic induction) in one of the circuits by a change of current in either of them. The term inductance coil is sometimes used as a synonym for inductor, a device possessing the property of inductance. See Electromagnetic induction, Electromotive force (emf), Inductor

For a given coil, the ratio of the electromotive force of induction to the rate of change of current in the coil is called the self-inductance of the coil. An alternative definition of self-inductance is the number of flux linkages per unit current. Flux linkage is the product of the flux and the number of turns in the coil. Self-inductance does not affect a circuit in which the current is unchanging; however, it is of great importance when there is a changing current, since there is an induced emf during the time that the change takes place. For example, in an alternating-current circuit, the current is constantly changing and the inductance is an important factor.

The mutual inductance of two neighboring circuits is defined as the ratio of the emf induced in one circuit to the rate of change of current in the other circuit.

The International System (SI) unit of mutual inductance is the henry, the same as the unit of self-inductance. The same value is obtained for a pair of coils, regardless of which coil is the starting point.

The mutual inductance of two circuits may also be expressed as the ratio of the flux linkages produced in a circuit by the current in a second circuit to the current in the second circuit. See Inductance measurement