This article is about the SI derived unit (Ω). For other meanings, see Ohm (disambiguation).
A multimeter can be used to measure resistance in ohms. It can also be used to measure voltage, current, and other electrical characteristics.

The ohm (symbol: Ω) is the SI derived unit of electrical resistance, named after German physicist Georg Simon Ohm.

Contents

Definition [link]

Several resistors. Their resistance, in ohms, is marked using a color code.

The ohm is defined as a resistance between two points of a conductor when a constant potential difference of 1 volt, applied to these points, produces in the conductor a current of 1 ampere, the conductor not being the seat of any electromotive force.[1]

Failed to parse (Missing texvc executable; please see math/README to configure.): \Omega = \dfrac{\mbox{V}}{\mbox{A}} = \dfrac{\mbox{m}^2 \cdot \mbox{kg}}{\mbox{s} \cdot \mbox{C}^2} = \dfrac{\mbox{J}}{\mbox{s} \cdot \mbox{A}^2}=\dfrac{\mbox{kg}\cdot\mbox{m}^2}{\mbox{s}^3 \cdot \mbox{A}^2}= \dfrac{\mbox{J} \cdot \mbox{s}}{\mbox{C}^2} = \dfrac{\mbox{1}}{\mbox{S}}


V=volt, A=ampere, m=meter, kg=kilogram, s=second, C=coulomb, J=joule, S=siemen

In many cases the resistance of a conductor in ohms is approximately constant within a certain range of voltages, temperatures, and other parameters; one speaks of linear resistors. In other cases resistance varies (e.g., thermistors).

Commonly used multiples and submultiples in electrical and electronic usage are the milliohm, ohm, kilohm, megohm, and gigaohm.[2]

In alternating current circuits, electrical impedance is also measured in ohms.

Conversions [link]

The siemens (symbol: S) is the SI derived unit of electric conductance and admittance, also known as the mho (ohm spelled backwards, symbol is ℧); it is the reciprocal of resistance in ohms.

Power as a function of resistance [link]

The power dissipated by a linear resistor may be calculated from its resistance, and voltage or current. The formula is a combination of Ohm's law and Joule's laws:

Failed to parse (Missing texvc executable; please see math/README to configure.): P=V\cdot I =\frac{V^2}{R} = I^2\cdot R

where P is the power in watts, R the resistance in ohms, V the voltage across the resistor, and I the current through it.

This formula is applicable to devices whose resistance varies with current.

Ohm symbol [link]

When preparing electronic documents, some document editing software will attempt to use the Symbol typeface to render the Ω character. Where the font is not supported, a W is displayed instead ("10 W" instead of "10 Ω", for instance). As W represents the watt, the SI unit of power, not resistance, this can lead to confusion.

An "R" can be used instead of the Ω symbol if it is not supported, thus, a 10 Ω resistor can also be represented as 10R. This is the British standard BS 1852 code. It is used in many instances where the value has a decimal place i.e. 5.6 Ω would be listed as 5R6. One advantage of this method is that it is relatively easy to "rub off" a decimal point symbol ".", changing the apparent value, compared to the "R" symbol, which would require more effort.

Unicode encodes the symbol as U+2126 Ω ohm sign, distinct from Greek omega among letterlike symbols, but it is only included for backwards compatibility and the Greek uppercase omega character U+03A9 Ω greek capital letter omega (HTML: Ω Ω) is preferred.[3] In DOS and Windows, the alt code ALT 234 may produce the Ω symbol.

See also [link]

References [link]

  1. ^ BIPM SI Brochure: Appendix 1, p. 144
  2. ^ The NIST Guide to the SI: 9.3 Spelling unit names with prefixes reports that IEEE/ASTM SI 10-2002 IEEE/ASTM Standard for Use of the International System of Units (SI): The Modern Metric System states that there are three cases in which the final vowel of an SI prefix is commonly omitted: megohm, kilohm, and hectare. "In all other cases in which the unit name begins with a vowel, both the final vowel of the prefix and the vowel of the unit name are retained and both are pronounced."
  3. ^ Excerpts from The Unicode Standard, Version 4.0, accessed 11 October 2006

External links [link]
Base units
Ampere · Candela · Kelvin · Kilogram · Metre · Mole · Second
SI base unit.svg
Derived units
Becquerel · Coulomb · Degree Celsius · Farad · Gray · Henry · Hertz · Joule · Katal · Lumen · Lux · Newton · Ohm · Pascal · Radian · Siemens · Sievert · Steradian · Tesla · Volt · Watt · Weber
Accepted for use
with SI
See also

https://wn.com/Ohm

OHM (band)

OHM (sometimes stylized Ohm: or OHM:) is an American instrumental rock/jazz fusion group fronted by former Megadeth guitarist Chris Poland. The band was formed in 2002 and has released three studio albums and a live album. A similar offshoot band named OHMphrey, also fronted by Poland, was formed in 2008.

The band often perform at the Baked Potato jazz club in Studio City, California.

Discography

Studio albums

  • 2003: OHM
  • 2005: Amino Acid Flashback
  • 2008: Circus of Sound

    • Live albums

  • 2004: "Live" on KPFK 90.7 FM

    • References

    External links

  • Chris Poland/OHM official site
    • Read more
    This page contains text from Wikipedia, the Free Encyclopedia - https://wn.com/OHM_(band)

    Ohm (disambiguation)

    Ohm (Ω) refers to the SI unit of electrical resistance named after Georg Ohm.

    Ohm may also refer to:

  • Ohm (crater) on the Moon
  • Ohm (river), a river in Germany
  • Ohm, California, a former settlement in the USA
  • Ohm (One Piece), a character featured in the Japanese anime One Piece
  • "Ohm," a song by indie band Yo La Tengo, included on the album Fade
  • Alternative spelling for Om, a mantra and sacred syllable of several Indian religions (in particular Dharma faiths like Hinduism, Jainism, and Buddhism).
  • Alternative spelling for Um (Korean name)
  • Georg Ohm (1789–1854), German physicist
  • Martin Ohm (1792–1872), German mathematician
  • German Ohm, Mexican boxer
  • Johnny Ohm, Marvel Comics supervillain
  • Thorsten Ohm, CEO of VDM Publishing
  • An obsolete unit of volume measurement, less than a litre, used in Prussia, Sweden and Denmark

    • OHM may refer to:

  • OHM (band), a rock/jazz fusion music group
  • OHM: The Early Gurus of Electronic Music, 2000 album
  • One Hot Minute, the sixth studio album by American alternative rock band Red Hot Chili Peppers
    • Read more
    This page contains text from Wikipedia, the Free Encyclopedia - https://wn.com/Ohm_(disambiguation)

    Wiseguy

    Wiseguy is an American crime drama series that aired on CBS from September 16, 1987 ,to December 8, 1990, for a total of 75 episodes. The series was produced by Stephen J. Cannell and was filmed in Vancouver, British Columbia, to avoid the higher studio costs associated with filming in Los Angeles.

    Wiseguy featured Ken Wahl as Vinnie Terranova, a deep cover operative for the fictional Organized Crime Task Force division of the FBI. Jonathan Banks played his superior Frank McPike and Jim Byrnes played Daniel "Lifeguard" Burroughs, who assisted Vinnie while in the field. Wahl left the series after three seasons and Steven Bauer joined the series alongside Banks and Byrnes, who were the only cast members to appear in every season.

    As opposed to a typical crime drama series, Wiseguy was structured more like a typical soap opera would be; for example, a cycle of episodes would focus on a particular story and the story would conclude in the final episode of the cycle, which gave rise to the term story arc. Since each cycle dealt with a particular story, the episodes had a set of characters written just for those episodes. Actors such as Kevin Spacey, Ray Sharkey, and Tim Curry were among the actors who played central characters in story arcs over the course of the series.

    Read more
    This page contains text from Wikipedia, the Free Encyclopedia - https://wn.com/Wiseguy

    Wiseguy (book)

    Wiseguy: Life in a Mafia Family (ISBN 0-671-44734-3) is a 1986 non-fiction book by crime reporter Nicholas Pileggi that chronicles the story of Mafia mobster-turned-informant Henry Hill. The book is the basis for the Academy Award-winning film Goodfellas (1990) directed by Martin Scorsese.

    Summary

    Henry Hill began his life of crime at age 11 in 1955, by working as a go-fer for Paul Vario, the local boss of Hill's working class Irish/Italian neighborhood. Eventually Hill was "promoted" to selling stolen cigarettes for Vario.

    Hill was first arrested in 1959, for using stolen credit cards. Hill refused to cooperate with the police, earning the respect of Vario and Vario's associate Jimmy Burke.

    In 1960, when Hill was 17, he enlisted in the United States Army, to everyone's surprise. When questioned about his decision by Vario, Hill explained that he wanted to please his father, who disapproved of his son's association with the Mafia. While stationed at Fort Bragg in North Carolina, however, Hill continued his criminal activities, which led to his discharge in 1963. He returned to the streets of New York, where he was happily welcomed back by Vario and Burke.

    Read more
    This page contains text from Wikipedia, the Free Encyclopedia - https://wn.com/Wiseguy_(book)

    List of recurring The Simpsons characters

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    Read more
    This page contains text from Wikipedia, the Free Encyclopedia - https://wn.com/List_of_recurring_The_Simpsons_characters

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