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<p><b>New page</b></p><div>[[File:Inductor.jpg|thumb|Inductor]] '''Henry (unit)''' is a [[unit of measurement]] in the [[International System of Units]] (SI) that is used to measure [[electrical inductance]]. It is denoted by the symbol '''H'''. One henry is defined as the amount of inductance in a [[circuit]] when a [[current]] change of one [[ampere]] per second results in an [[electromotive force]] (EMF) of one [[volt]]. The unit is named after [[Joseph Henry]], an American scientist who discovered the phenomenon of [[electromagnetic induction]] independently around the same time as [[Michael Faraday]] in England.<br />
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==Definition==<br />
The henry (H) can be defined in terms of basic SI units as:<br />
\[H = \frac{kg \cdot m^2}{s^2 \cdot A^2}\]<br />
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This definition relates to the physical quantities involved in inductance: the [[kilogram]] (kg) for mass, the [[meter]] (m) for distance, the [[second]] (s) for time, and the [[ampere]] (A) for electric current.<br />
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==Applications==<br />
Henry is a critical unit in the field of [[electronics]] and [[electrical engineering]]. It is used in the design and analysis of [[electrical circuits]], especially in [[inductors]], [[transformers]], and various types of [[electromagnetic]] devices. The value of inductance in a circuit affects its ability to store energy in a magnetic field and influences the circuit's response to changes in current. Devices with high inductance can be used to smooth out changes in current, making them essential in power supplies and [[radio]] [[frequency]] applications.<br />
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==Measurement==<br />
Inductance is typically measured using instruments such as [[LCR meters]], which can determine the inductance of a component by measuring its impedance at different frequencies. The henry is a relatively large unit, and in practical applications, submultiples are often used, such as the millihenry (mH, 1/1,000 of a henry) and the microhenry (μH, 1/1,000,000 of a henry).<br />
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==Historical Context==<br />
The henry is named after Joseph Henry (1797–1878), who made significant contributions to the understanding of electromagnetic induction, a fundamental principle in the field of electromagnetism. His work in the early 19th century laid the groundwork for the development of the electric telegraph and the electric motor. The unit was established to honor his contributions to science, particularly in the study of electromagnetism.<br />
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==See Also==<br />
* [[Electromagnetic induction]]<br />
* [[Inductor]]<br />
* [[Transformer]]<br />
* [[Electrical resistance]]<br />
* [[Capacitance]]<br />
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[[Category:SI derived units]]<br />
[[Category:Units of electrical inductance]]<br />
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