The henry (symbol: H) is the SI derived unit of electrical inductance. If a current of 1 ampere flowing through the coil produces flux linkage of 1 weber turn, the coil has a self inductance of 1 henry. The unit is named after Joseph Henry (1797–1878), the American scientist who discovered electromagnetic induction independently of and at about the same time as Michael Faraday (1791–1867) in England.
|Unit system||SI derived unit|
|Named after||Joseph Henry|
|In SI base units:||kg⋅m2⋅s−2⋅A−2|
where V(t) denotes the resulting voltage across the circuit, I(t) is the current through the circuit, and L is the inductance of the circuit.
The henry is a derived unit based on four of the seven base units of the International System of Units: kilogram (kg), metre (m), second (s), and ampere (A). Expressed in combinations of SI units, the henry is:
The International System of Units (SI) specifies to write the symbol of a unit named for a person with an initial capital letter, while the name is not capitalized in sentence text, except when any word in that position would be capitalized, such as at the beginning of a sentence or in material using title case.
The inductance of a coil depends on its size, the number of turns, and the permeability of the material within and surrounding the coil. Formulas can be used to calculate the inductance of many common arrangements of conductors, such as parallel wires, or a solenoid. A small air-core coil used for broadcast AM radio tuning might have an inductance of a few tens of microhenries. A large motor winding with many turns around an iron core may have an inductance of scores or hundreds of henries. The physical size of an inductance is also related to its current carrying and voltage withstand ratings.
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This glossary of electrical and electronics engineering pertains specifically to electrical and electronics engineering. For a broad overview of engineering, see glossary of engineering.Henry's
Henry's may refer to:
Henry's Amazing Animals - Disney Channel children's program
Henry's Amazing Golden Gecko Awards
Henry's Anger - Canberra heavy metal band
Henry's Fork Caldera - Caldera in Yellowstone National Park
Henry's Cat - animated children's television show
Henry's (clothiers) - Wichita company and AAU powerhouse
Henry's Dream - Nick Cave and the Bad Seeds album
Henry's Dress - Rock band from New Mexico
Henry's (electronics retailer) - Canadian retailer
Henry's Farmers Market (formerly Boney's Market) - Southern California retailer
Henry's House - London public relations firm
Henry's Knob - Superfund site in South Carolina
Henry's Lake National Forest - National forest in Idaho
Henry's law - a chemistry gas law
Henry's Grove - Berlin, Worcester County, Maryland
Sir Henry's - nightclub in Cork, Ireland
St. Henry's Church - church in Bayonne, New Jersey
Henry's Hamburgers - an american restaurant chainIndex of electrical engineering articles
This is an alphabetical list of articles pertaining specifically to electrical and electronics engineering. For a thematic list, please see List of electrical engineering topics. For a broad overview of engineering, see List of engineering topics. For biographies, see List of engineers.Index of electronics articles
This is an index of articles relating to electronics and electricity or natural electricity and things that run on electricity and things that use or conduct electricity.Index of physics articles (H)
The index of physics articles is split into multiple pages due to its size.
To navigate by individual letter use the table of contents below.Joseph Henry
Joseph Henry (December 17, 1797 – May 13, 1878) was an American scientist who served as the first Secretary of the Smithsonian Institution. He was the secretary for the National Institute for the Promotion of Science, a precursor of the Smithsonian Institution. He was highly regarded during his lifetime. While building electromagnets, Henry discovered the electromagnetic phenomenon of self-inductance. He also discovered mutual inductance independently of Michael Faraday, though Faraday was the first to make the discovery and publish his results. Henry developed the electromagnet into a practical device. He invented a precursor to the electric doorbell (specifically a bell that could be rung at a distance via an electric wire, 1831) and electric relay (1835). The SI unit of inductance, the Henry, is named in his honor. Henry's work on the electromagnetic relay was the basis of the practical electrical telegraph, invented by Samuel F. B. Morse and Sir Charles Wheatstone, separately.
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