henry

The word “henry” means the SI unit of electrical inductance, symbol H. In plain terms, either the classic English first name, or the scientific unit of inductance.

“Henry” is pronounced HEHN-ree (/ˈhɛn.ɹi/ in IPA).

Here is “henry” used in a sentence: “Henry VIII had six wives during his reign.”

Depending on how it is used, “henry” can be a noun and a name.

The word “henry” dates back to around 1797 and comes from Germanic. The unit is named after the American scientist Joseph Henry (1797-1878); the given name comes from Germanic roots meaning roughly "ruler of the home".

“Henry” is a very common word in modern English.

“Henry” has 2 distinct senses listed in this dictionary. The most common is: the SI unit of electrical inductance, symbol H.

The henry is the SI unit of electrical inductance, with the symbol H. Inductance measures how strongly a coil or circuit opposes a change in the electric current flowing through it. A component has an inductance of one henry when current changing at one ampere per second induces a voltage of one volt.

The henry is named after Joseph Henry, a nineteenth-century American scientist who independently discovered electromagnetic induction around the same time as Michael Faraday. Naming the unit after him honours his contribution to the study of inductance, following the convention of naming electrical units after their pioneering researchers.

By SI convention, units named after people are written in lowercase — henry, not Henry — even though the person's name is capitalised. The symbol, however, is capitalised as H. This rule keeps the unit distinct from the surname and applies to other units too, such as the watt and the volt.

Both 'henries' and 'henrys' are accepted plurals, with 'henries' being the more traditional form, so an inductor might be rated at several henries. As with the unit itself, the plural stays lowercase, while the symbol H never takes an 's' when written after a number.