The unit of electric induction; the induction in a circuit when the electro-motive force induced in this circuit is one volt, while the inducing current varies at the rate of one ampère a second.

Unit for measuring inductance.

the SI unit of electric inductance. A changing magnetic field induces an electric current in a loop of wire (or in a coil of many loops) located in the field. Although the induced voltage depends only on the rate at which the magnetic flux changes, measured in webers per second, the amount of the current depends also on the physical properties of the coil. A coil with an inductance of one henry requires a flux of one weber for each ampere of induced current. If, on the other hand, it is the current which changes, then the induced field will generate a potential difference within the coil: if the inductance is one henry a current change of one ampere per second generates a potential difference of one volt. The henry is a large unit; inductances in practical circuits are measured in millihenrys (mH) or microhenrys (µH). The unit is named for the American physicist Joseph Henry (1797-1878), one of several scientists who discovered independently how magnetic fields can be used to generate alternating currents. The plural is sometimes spelled henrys, but in English it is correct to spell it henries.

The electromagnetic unit of inductance or mutual inductance. The inductance of a circuit is 1 henry when a current variation of 1 ampere per second induces 1 volt. In electronics, smaller units are used, such as the millihenry (mH), which is one-thousandth of a henry (H), and the microhenry (µH) which is one-millionth of a henry.