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93-460: The ampere ( / ˈ æ m p ɛər / AM -pair , US : / ˈ æ m p ɪər / AM -peer ; symbol: A ), often shortened to amp , is the unit of electric current in the International System of Units (SI). One ampere is equal to 1 coulomb (C) moving past a point per second. It is named after French mathematician and physicist André-Marie Ampère (1775–1836), considered

186-698: A cot–caught merger , which is rapidly spreading throughout the whole country. However, the South, Inland North, and a Northeastern coastal corridor passing through Rhode Island, New York City, Philadelphia, and Baltimore typically preserve an older cot–caught distinction. For that Northeastern corridor, the realization of the THOUGHT vowel is particularly marked , as depicted in humorous spellings, like in tawk and cawfee ( talk and coffee ), which intend to represent it being tense and diphthongal : [oə] . A split of TRAP into two separate phonemes , using different

279-493: A magnetic field of strength B {\displaystyle B} experiences a Lorentz force equal to the product of these variables. In the Kibble balance, the current is varied so that this force counteracts the weight w {\displaystyle w} of a mass m {\displaystyle m} to be measured. This principle is derived from the ampere balance. w {\displaystyle w}

372-520: A pronunciations for example in gap [æ] versus gas [eə] , further defines New York City as well as Philadelphia–Baltimore accents. Most Americans preserve all historical /r/ sounds, using what is known as a rhotic accent . The only traditional r -dropping (or non-rhoticity) in regional U.S. accents variably appears today in eastern New England , New York City , and some of the former plantation South primarily among older speakers (and, relatedly, some African-American Vernacular English across

465-404: A balance scale, with a counterbalance mass on the other side. The system operates by alternating between two modes: "weighing" and "moving". The entire mechanical subsystem operates in a vacuum chamber to remove the effects of air buoyancy. While "weighing", the system measures both I {\displaystyle I} and v {\displaystyle v} . The system controls

558-616: A complex phenomenon of "both convergence and divergence": some accents are homogenizing and leveling , while others are diversifying and deviating further away from one another. Having been settled longer than the American West Coast, the East Coast has had more time to develop unique accents, and it currently comprises three or four linguistically significant regions, each of which possesses English varieties both different from each other as well as quite internally diverse: New England ,

651-447: A consonant, such as in pearl , car and fort . Non-rhotic American accents, those that do not pronounce ⟨r⟩ except before a vowel, such as some accents of Eastern New England , New York City , and African-Americans , and a specific few (often older ones) spoken by Southerners , are often quickly noticed by General American listeners and perceived as sounding especially ethnic, regional, or antiquated. Rhoticity

744-422: A force equal to 2 × 10 newtons per metre of length. Ampère's force law states that there is an attractive or repulsive force between two parallel wires carrying an electric current. This force is used in the formal definition of the ampere. The SI unit of charge, the coulomb , was then defined as "the quantity of electricity carried in 1 second by a current of 1 ampere". Conversely, a current of one ampere

837-577: A location due to changes in underground water tables, and larger semimonthly and diurnal changes due to tidal distortions in the Earth's shape caused by the Moon and the Sun. Although g is not a term in the definition of the kilogram, it is crucial in the process of measurement of the kilogram when relating energy to power in a kibble balance. Accordingly, g must be measured with at least as much precision and accuracy as are

930-586: A merger with the THOUGHT ( caught ) set. Having taken place prior to the unrounding of the cot vowel, it results in lengthening and perhaps raising, merging the more recently separated vowel into the THOUGHT vowel in the following environments: before many instances of /f/ , /θ/ , and particularly /s/ (as in Austria, cloth, cost, loss, off, often, etc.), a few instances before /ŋ/ (as in strong, long, wrong ), and variably by region or speaker in gone , on , and certain other words. Unlike American accents,

1023-636: A nice day , for sure); many are now distinctly old-fashioned (swell, groovy). Some English words now in general use, such as hijacking, disc jockey , boost, bulldoze and jazz , originated as American slang. American English has always shown a marked tendency to use words in different parts of speech and nouns are often used as verbs . Examples of nouns that are now also verbs are interview, advocate, vacuum, lobby, pressure, rear-end, transition, feature, profile, hashtag, head, divorce, loan, estimate, X-ray, spearhead, skyrocket, showcase, bad-mouth, vacation , major, and many others. Compounds coined in

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1116-475: A process of extensive dialect mixture and leveling in which English varieties across the colonies became more homogeneous compared with the varieties in Britain. English thus predominated in the colonies even by the end of the 17th century's first immigration of non-English speakers from Western Europe and Africa. Additionally, firsthand descriptions of a fairly uniform American English (particularly in contrast to

1209-553: A second. Prior to the redefinition the ampere was defined as the current passing through two parallel wires 1 metre apart that produces a magnetic force of 2 × 10 newtons per metre. The earlier CGS system has two units of current, one structured similarly to the SI's and the other using Coulomb's law as a fundamental relationship, with the CGS unit of charge defined by measuring the force between two charged metal plates. The CGS unit of current

1302-657: A series of other vowel shifts in the same region, known by linguists as the " Inland North ". The Inland North shares with the Eastern New England dialect (including Boston accents ) a backer tongue positioning of the GOOSE /u/ vowel (to [u] ) and the MOUTH /aʊ/ vowel (to [ɑʊ~äʊ] ) in comparison to the rest of the country. Ranging from northern New England across the Great Lakes to Minnesota, another Northern regional marker

1395-514: A survey, completed in 2003, polling English speakers across the United States about their specific everyday word choices, hoping to identify regionalisms. The study found that most Americans prefer the term sub for a long sandwich, soda (but pop in the Great Lakes region and generic coke in the South) for a sweet and bubbly soft drink , you or you guys for the plural of you (but y'all in

1488-453: A variation of American English in these islands. In 2021, about 245 million Americans, aged 5 or above, spoke English at home: a majority of the United States total population of roughly 330 million people. The United States has never had an official language at the federal level, but English is commonly used at the federal level and in states without an official language. 32 of the 50 states, in some cases as part of what has been called

1581-642: Is also associated with the United States, perhaps mostly in the Midwest and the South. American accents that have not undergone the cot–caught merger (the lexical sets LOT and THOUGHT ) have instead retained a LOT – CLOTH split : a 17th-century distinction in which certain words (labeled as the CLOTH lexical set ) separated away from the LOT set. The split, which has now reversed in most British English, simultaneously shifts this relatively recent CLOTH set into

1674-637: Is also home to a creole language known commonly as Hawaiian Pidgin , and some Hawaii residents speak English with a Pidgin-influenced accent. American English also gave rise to some dialects outside the country, for example, Philippine English , beginning during the American occupation of the Philippines and subsequently the Insular Government of the Philippine Islands ; Thomasites first established

1767-526: Is common in most American accents despite being now rare in England because, during the 17th-century British colonization, nearly all dialects of English were rhotic, and most North American English simply remained that way. The preservation of rhoticity in North America was also supported by continuing waves of rhotic-accented Scotch-Irish immigrants, most intensely during the 18th century (and moderately during

1860-401: Is determined by steady current I flowing for a time t as Q = I t . Constant, instantaneous and average current are expressed in amperes (as in "the charging current is 1.2 A") and the charge accumulated (or passed through a circuit) over a period of time is expressed in coulombs (as in "the battery charge is 30 000  C "). The relation of the ampere (C/s) to the coulomb is

1953-405: Is given by the mass m {\displaystyle m} multiplied by the local gravitational acceleration g {\displaystyle g} . Thus, The Kibble balance avoids the problems of measuring B {\displaystyle B} and L {\displaystyle L} in a second calibration step. The same wire (in practice, a coil) is moved through

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2046-420: Is often identified by Americans as a "country" accent, and is defined by the /aɪ/ vowel losing its gliding quality : [aː] , the initiation event for a complicated Southern vowel shift, including a " Southern drawl " that makes short front vowels into distinct-sounding gliding vowels . The fronting of the vowels of GOOSE , GOAT , MOUTH , and STRUT tends to also define Southern accents as well as

2139-486: Is one coulomb of charge going past a given point per second: In general, charge Q was determined by steady current I flowing for a time t as Q = It . This definition of the ampere was most accurately realised using a Kibble balance , but in practice the unit was maintained via Ohm's law from the units of electromotive force and resistance , the volt and the ohm , since the latter two could be tied to physical phenomena that are relatively easy to reproduce,

2232-584: Is the common language at home, in public, and in government. Kibble balance It was originally known as a watt balance because the weight of the test mass is proportional to the product of current and voltage, which is measured in watts . In June 2016, two months after the death of its inventor, Bryan Kibble , metrologists of the Consultative Committee for Units of the International Committee for Weights and Measures agreed to rename

2325-635: Is the set of varieties of the English language native to the United States. English is the most widely spoken language in the United States ; the de facto common language used in government, education, and commerce; and an official language in 32 of the 50 U.S. states . Since the late 20th century, American English has become the most influential form of English worldwide. Varieties of American English include many patterns of pronunciation, vocabulary, grammar and particularly spelling that are unified nationwide but distinct from other English dialects around

2418-463: Is the variable fronting of /ɑ/ before /r/ , for example, appearing four times in the stereotypical Boston shibboleth Park the car in Harvard Yard . Several other phenomena serve to distinguish regional U.S. accents. Boston , Pittsburgh , Upper Midwestern , and Western U.S. accents have fully completed a merger of the LOT vowel with the THOUGHT vowel ( /ɑ/ and /ɔ/ , respectively):

2511-411: Is then defined as one unit of charge per second. The ampere is named for French physicist and mathematician André-Marie Ampère (1775–1836), who studied electromagnetism and laid the foundation of electrodynamics . In recognition of Ampère's contributions to the creation of modern electrical science, an international convention, signed at the 1881 International Exposition of Electricity , established

2604-574: Is used in the Kibble balance was proposed by Bryan Kibble (1938-2016) of the UK National Physical Laboratory (NPL) in 1975 for measurement of the gyromagnetic ratio . In 1978 the Mark I watt balance was built at the NPL with Ian Robinson and Ray Smith. It operated until 1988. The main weakness of the ampere balance method is that the result depends on the accuracy with which the dimensions of

2697-476: The English-only movement , have adopted legislation granting official or co-official status to English. Typically only "English" is specified, not a particular variety like American English. (From 1923 to 1969, the state of Illinois recognized its official language as "American", meaning American English.) Puerto Rico is the largest example of a United States territory in which another language – Spanish –

2790-464: The Josephson effect and the quantum Hall effect , respectively. Techniques to establish the realisation of an ampere had a relative uncertainty of approximately a few parts in 10, and involved realisations of the watt, the ohm and the volt. The 2019 revision of the SI defined the ampere by taking the fixed numerical value of the elementary charge e to be 1.602 176 634 × 10 when expressed in

2883-608: The Mid-Atlantic states (including a New York accent as well as a unique Philadelphia–Baltimore accent ), and the South . As of the 20th century, the middle and eastern Great Lakes area , Chicago being the largest city with these speakers, also ushered in certain unique features, including the fronting of the LOT /ɑ/ vowel in the mouth toward [a] and tensing of the TRAP /æ/ vowel wholesale to [eə] . These sound changes have triggered

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2976-544: The Native American languages . Examples of such names are opossum , raccoon , squash , moose (from Algonquian ), wigwam , and moccasin . American English speakers have integrated traditionally non-English terms and expressions into the mainstream cultural lexicon; for instance, en masse , from French ; cookie , from Dutch ; kindergarten from German , and rodeo from Spanish . Landscape features are often loanwords from French or Spanish, and

3069-525: The Planck constant h {\displaystyle h} : The principle of the electronic kilogram relies on the value of the Planck constant, which is as of 2019 an exact value. This is similar to the metre being defined by the speed of light . With the constant defined exactly, the Kibble balance is not an instrument to measure the Planck constant, but is instead an instrument to measure mass: Gravity and

3162-408: The ampere balance , an early current measuring instrument in which the force between two current-carrying coils of wire is measured and then used to calculate the magnitude of the current. The Kibble balance operates in the opposite sense; the current in the coils set very precisely by the Planck constant , and the force between the coils is used to measure the weight of a test kilogram mass. Then

3255-714: The francophile tastes of the 19th century Victorian era Britain (for example they preferred programme for program , manoeuvre for maneuver , cheque for check , etc.). AmE almost always uses -ize in words like realize . BrE prefers -ise , but also uses -ize on occasion (see: Oxford spelling ). There are a few differences in punctuation rules. British English is more tolerant of run-on sentences , called " comma splices " in American English, and American English prefers that periods and commas be placed inside closing quotation marks even in cases in which British rules would place them outside. American English also favors

3348-759: The 18th century; apartment , shanty in the 19th century; project, condominium , townhouse , mobile home in the 20th century; and parts thereof ( driveway , breezeway, backyard ) . Industry and material innovations from the 19th century onwards provide distinctive new words, phrases, and idioms through railroading (see further at rail terminology ) and transportation terminology, ranging from types of roads ( dirt roads , freeways ) to infrastructure ( parking lot , overpass , rest area ), to automotive terminology often now standard in English internationally. Already existing English words—such as store , shop , lumber —underwent shifts in meaning; others remained in

3441-534: The 20th century. The use of English in the United States is a result of British colonization of the Americas . The first wave of English-speaking settlers arrived in North America during the early 17th century, followed by further migrations in the 18th and 19th centuries. During the 17th and 18th centuries, dialects from many different regions of England and the British Isles existed in every American colony, allowing

3534-622: The British form is a back-formation , such as AmE burglarize and BrE burgle (from burglar ). However, while individuals usually use one or the other, both forms will be widely understood and mostly used alongside each other within the two systems. While written American English is largely standardized across the country and spoken American English dialects are highly mutually intelligible, there are still several recognizable regional and ethnic accents and lexical distinctions. The regional sounds of present-day American English are reportedly engaged in

3627-447: The CGPM voted unanimously on November 16, 2018, to change the definition of the kilogram and several other units , effective May 20, 2019, to coincide with World Metrology Day . There is also a method called the joule balance . All methods that use the fixed numerical value of the Planck constant are sometimes called the Planck balance. The Kibble balance is a more accurate version of

3720-413: The East Coast (perhaps in imitation of 19th-century London speech), even the East Coast has gradually begun to restore rhoticity, due to it becoming nationally prestigious in the 20th century. The pronunciation of ⟨r⟩ is a postalveolar approximant [ ɹ̠ ] or retroflex approximant [ ɻ ] , but a unique "bunched tongue" variant of the approximant r sound

3813-565: The Inland North. Rather than one particular accent, General American is best defined as an umbrella covering an American accent that does not incorporate features associated with some particular region, ethnicity, or socioeconomic group. Typical General American features include rhoticity , the father–bother merger , Mary–marry–merry merger , pre-nasal "short a " tensing , and other particular vowel sounds . General American features are embraced most by Americans who are highly educated or in

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3906-490: The International System of Units; hence the original name "watt balance". The product B L {\displaystyle BL} , also called the geometric factor, is not trivially equal in both calibration steps. The geometric factor is only constant under certain stability conditions on the coil. The Kibble balance is constructed so that the mass to be measured and the wire coil are suspended from one side of

3999-572: The SI unit of mass: the kilogram. The Kibble balance originating from the National Physical Laboratory was transferred to the National Research Council of Canada (NRC) in 2009, where scientists from the two labs continued to refine the instrument. In 2014, NRC researchers published the most accurate measurement of the Planck constant at that time, with a relative uncertainty of 1.8 × 10 . A final paper by NRC researchers

4092-560: The South), sneakers for athletic shoes (but often tennis shoes outside the Northeast), and shopping cart for a cart used for carrying supermarket goods. American English and British English (BrE) often differ at the levels of phonology, phonetics, vocabulary, and, to a much lesser extent, grammar and orthography. The first large American dictionary, An American Dictionary of the English Language , known as Webster's Dictionary ,

4185-528: The U.S. Several verbs ending in -ize are of U.S. origin; for example, fetishize, prioritize, burglarize, accessorize, weatherize , etc.; and so are some back-formations (locate, fine-tune, curate, donate, emote, upholster and enthuse). Among syntactic constructions that arose are outside of, headed for, meet up with, back of, etc. Americanisms formed by alteration of some existing words include notably pesky, phony, rambunctious, buddy, sundae , skeeter, sashay and kitty-corner. Adjectives that arose in

4278-563: The U.S. are for instance foothill , landslide (in all senses), backdrop , teenager , brainstorm , bandwagon , hitchhike , smalltime, and a huge number of others. Other compound words have been founded based on industrialization and the wave of the automobile: five-passenger car, four-door sedan, two-door sedan, and station-wagon (called an estate car in British English). Some are euphemistic ( human resources , affirmative action , correctional facility ). Many compound nouns have

4371-662: The U.S. are, for example, lengthy, bossy, cute and cutesy, punk (in all senses), sticky (of the weather), through (as in "finished"), and many colloquial forms such as peppy or wacky . A number of words and meanings that originated in Middle English or Early Modern English and that have been in everyday use in the United States have since disappeared in most varieties of British English; some of these have cognates in Lowland Scots . Terms such as fall ("autumn"), faucet ("tap"), diaper ("nappy"; itself unused in

4464-530: The U.S. while changing in Britain. Science, urbanization, and democracy have been important factors in bringing about changes in the written and spoken language of the United States. From the world of business and finance came new terms ( merger , downsize , bottom line ), from sports and gambling terminology came, specific jargon aside, common everyday American idioms, including many idioms related to baseball . The names of some American inventions remained largely confined to North America ( elevator [except in

4557-427: The U.S.), candy ("sweets"), skillet , eyeglasses , and obligate are often regarded as Americanisms. Fall for example came to denote the season in 16th century England, a contraction of Middle English expressions like "fall of the leaf" and "fall of the year." Gotten ( past participle of get ) is often considered to be largely an Americanism. Other words and meanings were brought back to Britain from

4650-592: The U.S., especially in the second half of the 20th century; these include hire ("to employ"), I guess (famously criticized by H. W. Fowler ), baggage , hit (a place), and the adverbs overly and presently ("currently"). Some of these, for example, monkey wrench and wastebasket , originated in 19th century Britain. The adjectives mad meaning "angry", smart meaning "intelligent", and sick meaning "ill" are also more frequent in American (and Irish) English than British English. Linguist Bert Vaux created

4743-531: The United States and the United Kingdom suggest that, while spoken American English deviated away from period British English in many ways, it is conservative in a few other ways, preserving certain features 21st-century British English has since lost. Full rhoticity (or "R-fulness") is typical of American accents, pronouncing the phoneme /r/ (corresponding to the letter ⟨r⟩ ) in all environments, including in syllable-final position or before

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4836-596: The West and Midwest, and New York Latino English , spoken in the New York metropolitan area . Additionally, ethnic varieties such as Yeshiva English and " Yinglish " are spoken by some American Orthodox Jews , Cajun Vernacular English by some Cajuns in southern Louisiana , and Pennsylvania Dutch English by some Pennsylvania Dutch people. American Indian Englishes have been documented among diverse Indian tribes. The island state of Hawaii , though primarily English-speaking,

4929-547: The accents spoken in the " Midland ": a vast band of the country that constitutes an intermediate dialect region between the traditional North and South. Western U.S. accents mostly fall under the General American spectrum. Below, ten major American English accents are defined by their particular combinations of certain vowel sounds: In 2010, William Labov noted that Great Lakes, Philadelphia, Pittsburgh, and West Coast accents have undergone "vigorous new sound changes" since

5022-505: The aeronautical sense ], gasoline ) as did certain automotive terms ( truck , trunk ). New foreign loanwords came with 19th and early 20th century European immigration to the U.S.; notably, from Yiddish ( chutzpah , schmooze, bupkis, glitch ) and German ( hamburger , wiener ). A large number of English colloquialisms from various periods are American in origin; some have lost their American flavor (from OK and cool to nerd and 24/7 ), while others have not ( have

5115-466: The ampere are: There are also some SI units that are frequently used in the context of electrical engineering and electrical appliances, but are defined independently of the ampere, notably the hertz , joule, watt, candela, lumen , and lux. Like other SI units, the ampere can be modified by adding a prefix that multiplies it by a power of 10 . American English American English , sometimes called United States English or U.S. English ,

5208-401: The ampere as a standard unit of electrical measurement for electric current. The ampere was originally defined as one tenth of the unit of electric current in the centimetre–gram–second system of units . That unit, now known as the abampere , was defined as the amount of current that generates a force of two dynes per centimetre of length between two wires one centimetre apart. The size of

5301-399: The coils are measured. The Kibble balance uses an extra calibration step to cancel the effect of the geometry of the coils, removing the main source of uncertainty. This extra step involves moving the force coil through a known magnetic flux at a known speed. This was possible by setting of the conventional values of the von Klitzing constant and Josephson constant , which are used throughout

5394-478: The constancy of the speed of light as well as the innate properties of helium, neon, and rubidium atoms, the 'gravity' term in the delineation of an all-electronic kilogram is also measured in terms of invariants of nature—and with very high precision. For instance, in the basement of the NIST's Gaithersburg facility in 2009, when measuring the gravity acting upon Pt‑10Ir test masses (which are denser, smaller, and have

5487-406: The country), though the vowel-consonant cluster found in "bird", "work", "hurt", "learn", etc. usually retains its r pronunciation, even in these non-rhotic American accents. Non-rhoticity among such speakers is presumed to have arisen from their upper classes' close historical contact with England, imitating London's r -dropping, a feature that has continued to gain prestige throughout England from

5580-472: The current in the coil to pull the coil through a magnetic field at a constant velocity v {\displaystyle v} . Coil position and velocity measurement circuitry uses an interferometer together with a precision clock input to determine the velocity and control the current needed to maintain it. The required current is measured, using an ammeter comprising a Josephson junction voltage standard and an integrating voltmeter. While "moving",

5673-586: The device in his honor. Prior to 2019, the definition of the kilogram was based on a physical object known as the International Prototype of the Kilogram (IPK). After considering alternatives , in 2013 the General Conference on Weights and Measures (CGPM) agreed on accuracy criteria for replacing this definition with one based on the use of a Kibble balance. After these criteria had been achieved,

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5766-614: The diverse regional dialects of British English) became common after the mid-18th century, while at the same time speakers' identification with this new variety increased. Since the 18th century, American English has developed into some new varieties, including regional dialects that retain minor influences from waves of immigrant speakers of diverse languages, primarily European languages. Some racial and regional variation in American English reflects these groups' geographic settlement, their de jure or de facto segregation, and patterns in their resettlement. This can be seen, for example, in

5859-742: The double quotation mark ("like this") over the single ('as here'). Vocabulary differences vary by region. For example, autumn is used more commonly in the United Kingdom, whereas fall is more common in American English. Some other differences include: aerial (United Kingdom) vs. antenna, biscuit (United Kingdom) vs. cookie/cracker, car park (United Kingdom) vs. parking lot, caravan (United Kingdom) vs. trailer, city centre (United Kingdom) vs. downtown, flat (United Kingdom) vs. apartment, fringe (United Kingdom) vs. bangs, and holiday (United Kingdom) vs. vacation. AmE sometimes favors words that are morphologically more complex, whereas BrE uses clipped forms, such as AmE transportation and BrE transport or where

5952-403: The equations to give With U {\displaystyle U} , I {\displaystyle I} , g {\displaystyle g} , and v {\displaystyle v} accurately measured, this gives an accurate value for m {\displaystyle m} . Both sides of the equation have the dimensions of power , measured in watts in

6045-508: The experimental error. Accurate measurements of electric current and potential difference are made in conventional electrical units (rather than SI units), which are based on fixed " conventional values " of the Josephson constant and the von Klitzing constant , K J-90 {\displaystyle K_{\text{J-90}}} and R K-90 {\displaystyle R_{\text{K-90}}} respectively. The current Kibble balance experiments are equivalent to measuring

6138-410: The father of electromagnetism along with Danish physicist Hans Christian Ørsted . As of the 2019 revision of the SI , the ampere is defined by fixing the elementary charge e to be exactly 1.602 176 634 × 10 C , which means an ampere is an electric current equivalent to 10 elementary charges moving every 1.602 176 634 seconds or 6.241 509 074 × 10 elementary charges moving in

6231-510: The following two centuries) when this ethnic group eventually made up one-seventh of the colonial population. Scotch-Irish settlers spread from Delaware and Pennsylvania throughout the larger Mid-Atlantic region, the inland regions of both the South and North, and throughout the West: American dialect areas that were all uninfluenced by upper-class non-rhoticity and that consequently have remained consistently rhotic. While non-rhoticity spread on

6324-939: The hospital , BrE to hospital ; contrast, however, AmE actress Elizabeth Taylor , BrE the actress Elizabeth Taylor ). Often, these differences are a matter of relative preferences rather than absolute rules; and most are not stable since the two varieties are constantly influencing each other, and American English is not a standardized set of dialects. Differences in orthography are also minor. The main differences are that American English usually uses spellings such as flavor for British flavour , fiber for fibre , defense for defence , analyze for analyse , license for licence , catalog for catalogue and traveling for travelling . Noah Webster popularized such spellings in America, but he did not invent most of them. Rather, "he chose already existing options on such grounds as simplicity, analogy or etymology." Other differences are due to

6417-656: The influence of 18th-century Protestant Ulster Scots immigrants (known in the U.S. as the Scotch-Irish ) in Appalachia developing Appalachian English and the 20th-century Great Migration bringing African-American Vernacular English to the Great Lakes urban centers. Any phonologically unmarked North American accent falls under an umbrella known as General American. This section mostly refers to such General American features. Studies on historical usage of English in both

6510-438: The late 18th century onwards, but which has conversely lost prestige in the U.S. since at least the early 20th century. Non-rhoticity makes a word like car sound like cah or source like sauce . New York City and Southern accents are the most prominent regional accents of the country, as well as the most stigmatized and socially disfavored. Southern speech, strongest in southern Appalachia and certain areas of Texas,

6603-460: The local gravitational acceleration g {\displaystyle g} , because g {\displaystyle g} does not vary rapidly with time. Instead, g {\displaystyle g} is measured in the same laboratory using a highly accurate and precise gravimeter . In addition, the balance depends on a highly accurate and precise frequency reference such as an atomic clock to compute voltage and current. Thus,

6696-461: The mass is calculated from the weight by accurately measuring the local Earth's gravity (the net acceleration combining gravitational and centrifugal effects) with a gravimeter . Thus the mass of the object is defined in terms of a current and a voltage — allowing the device to "measure mass without recourse to the IPK ( International Prototype Kilogram ) or any physical object". The principle that

6789-427: The mid-nineteenth century onwards, so they "are now more different from each other than they were 50 or 100 years ago", while other accents, like of New York City and Boston, have remained stable in that same time-frame. However, a General American sound system also has some debated degree of influence nationwide, for example, gradually beginning to oust the regional accent in urban areas of the South and at least some in

6882-617: The most formal contexts, and regional accents with the most General American native features include North Midland, Western New England, and Western accents. Although no longer region-specific, African-American Vernacular English , which remains the native variety of most working- and middle-class African Americans , has a close relationship to Southern dialects and has greatly influenced everyday speech of many Americans, including hip hop culture . Hispanic and Latino Americans have also developed native-speaker varieties of English. The best-studied Latino Englishes are Chicano English , spoken in

6975-565: The nanonewton to micronewton range traceably to the SI-defined physical constants via electrical and optical measurements. Due to their small scale, MEMS Kibble balances typically use electrostatic rather than the inductive forces used in larger instruments. Lateral and torsional variants have also been demonstrated, with the main application (as of 2019) being in the calibration of the atomic force microscope . Accurate measurements by several teams will enable their results to be averaged and so reduce

7068-458: The nature of the Kibble balance, which oscillates test masses up and down against the local gravitational acceleration g , are exploited so that mechanical power is compared against electrical power, which is the square of voltage divided by electrical resistance. However, g varies significantly—by nearly 1%—depending on where on the Earth's surface the measurement is made (see Earth's gravity ). There are also slight seasonal variations in g at

7161-472: The other terms, so measurements of g must also be traceable to fundamental constants of nature. For the most precise work in mass metrology, g is measured using dropping-mass absolute gravimeters that contain an iodine-stabilised helium–neon laser interferometer . The fringe-signal , frequency-sweep output from the interferometer is measured with a rubidium atomic clock . Since this type of dropping-mass gravimeter derives its accuracy and stability from

7254-402: The past forms of a few verbs (for example, AmE/BrE: learned / learnt , burned / burnt , snuck/sneaked , dove/dived ) although the purportedly "British" forms can occasionally be seen in American English writing as well; different prepositions and adverbs in certain contexts (for example, AmE in school, BrE at school ); and whether or not a definite article is used, in very few cases (AmE to

7347-718: The precision and accuracy of the mass measurement depends on the Kibble balance, the gravimeter, and the clock. Like the early atomic clocks, the early Kibble balances were one-of-a-kind experimental devices and were large, expensive, and delicate. As of 2019, work is underway to produce standardized devices at prices that permit use in any metrology laboratory that requires high-precision measurement of mass. As well as large Kibble balances, microfabricated or MEMS watt balances (now called Kibble balances) have been demonstrated since around 2003. These are fabricated on single silicon dies similar to those used in microelectronics and accelerometers, and are capable of measuring small forces in

7440-575: The product of current and voltage, the ampere can alternatively be expressed in terms of the other units using the relationship I = P / V , and thus 1 A = 1 W/V. Current can be measured by a multimeter , a device that can measure electrical voltage, current, and resistance. Until 2019, the SI defined the ampere as follows: The ampere is that constant current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross-section, and placed one metre apart in vacuum, would produce between these conductors

7533-639: The same as that of the watt (J/s) to the joule . The international system of units (SI) is based on seven SI base units the second , metre, kilogram , kelvin , ampere, mole , and candela representing seven fundamental types of physical quantity, or "dimensions" , ( time , length , mass , temperature , electric current, amount of substance , and luminous intensity respectively) with all other SI units being defined using these. These SI derived units can either be given special names e.g. watt, volt, lux , etc. or defined in terms of others, e.g. metre per second . The units with special names derived from

7626-408: The same magnetic field at a known speed v {\displaystyle v} . By Faraday's law of induction , a potential difference U {\displaystyle U} is generated across the ends of the wire, which equals B L v {\displaystyle BLv} . Thus The unknown product B L {\displaystyle BL} can be eliminated from

7719-627: The system measures U {\displaystyle U} . The system ceases to provide current to the coil. This allows the counterbalance to pull the coil (and mass) upward through the magnetic field, which causes a voltage difference across the coil. The velocity measurement circuitry measures the speed of movement of the coil. This voltage is measured, using the same voltage standard and integrating voltmeter. A typical Kibble balance measures U {\displaystyle U} , I {\displaystyle I} , and v {\displaystyle v} , but does not measure

7812-570: The traditional standard accent of (southern) England, Received Pronunciation (RP), has evolved a trap–bath split . Moreover, American accents preserve /h/ at the start of syllables, while perhaps a majority of the regional dialects of England participate in /h/ dropping , particularly in informal contexts. However, General American is also innovative in a number of its own ways: The process of coining new lexical items started as soon as English-speaking British-American colonists began borrowing names for unfamiliar flora, fauna, and topography from

7905-416: The unit C, which is equal to A⋅s, where the second is defined in terms of ∆ ν Cs , the unperturbed ground state hyperfine transition frequency of the caesium -133 atom. The SI unit of charge, the coulomb , "is the quantity of electricity carried in 1 second by a current of 1 ampere". Conversely, a current of one ampere is one coulomb of charge going past a given point per second: In general, charge Q

7998-453: The unit was chosen so that the units derived from it in the MKSA system would be conveniently sized. The "international ampere" was an early realization of the ampere, defined as the current that would deposit 0.001 118  grams of silver per second from a silver nitrate solution. Later, more accurate measurements revealed that this current is 0.999 85  A . Since power is defined as

8091-420: The value of the conventional watt in SI units. From the definition of the conventional watt, this is equivalent to measuring the value of the product K J 2 R K {\displaystyle K_{\text{J}}^{2}R_{\text{K}}} in SI units instead of its fixed value in conventional electrical units: The importance of such measurements is that they are also a direct measurement of

8184-417: The verb-and-preposition combination: stopover, lineup, tryout, spin-off, shootout , holdup, hideout, comeback, makeover , and many more. Some prepositional and phrasal verbs are in fact of American origin ( win out, hold up, back up/off/down/out, face up to and many others). Noun endings such as -ee (retiree), -ery (bakery), -ster (gangster) and -cian (beautician) are also particularly productive in

8277-772: The word corn , used in England to refer to wheat (or any cereal), came to denote the maize plant, the most important crop in the U.S. Most Mexican Spanish contributions came after the War of 1812 , with the opening of the West, like ranch (now a common house style ). Due to Mexican culinary influence, many Spanish words are incorporated in general use when talking about certain popular dishes: cilantro (instead of coriander), queso, tacos, quesadillas, enchiladas, tostadas, fajitas, burritos, and guacamole. These words usually lack an English equivalent and are found in popular restaurants. New forms of dwelling created new terms ( lot , waterfront) and types of homes like log cabin , adobe in

8370-456: The world for voltage and resistance calibration. Using these principles, in 1990 Bryan Kibble and Ian Robinson invented the Kibble Mark II balance, which uses a circular coil and operates in vacuum conditions . Bryan Kibble worked with Ian Robinson and Janet Belliss to build this Mark Two version of the balance. This design allowed for measurements accurate enough for use in the redefinition of

8463-609: The world. Any American or Canadian accent perceived as lacking noticeably local, ethnic, or cultural markers is known in linguistics as General American ; it covers a fairly uniform accent continuum native to certain regions of the U.S. but especially associated with broadcast mass media and highly educated speech. However, historical and present linguistic evidence does not support the notion of there being one single mainstream American accent . The sound of American English continues to evolve, with some local accents disappearing, but several larger regional accents having emerged in

8556-1012: Was published in May 2017, presenting a measurement of the Planck constant with an uncertainty of only 9.1 parts per billion, the measurement with the least uncertainty to that date. Other Kibble balance experiments are conducted in the US National Institute of Standards and Technology (NIST), the Swiss Federal Office of Metrology (METAS) in Berne, the International Bureau of Weights and Measures (BIPM) near Paris and Laboratoire national de métrologie et d’essais (LNE) in Trappes , France. A conducting wire of length L {\displaystyle L} that carries an electric current I {\displaystyle I} perpendicular to

8649-469: Was written by Noah Webster in 1828, codifying several of these spellings. Differences in grammar are relatively minor, and do not normally affect mutual intelligibility; these include: typically a lack of differentiation between adjectives and adverbs, employing the equivalent adjectives as adverbs he ran quick / he ran quickly ; different use of some auxiliary verbs ; formal (rather than notional) agreement with collective nouns ; different preferences for

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