Carey Foster bridge

This article includes a list of references, related reading, or external links, but its sources remain unclear because it lacks inline citations. Please help improve this article by introducing more precise citations. (January 2013) (Learn how and when to remove this message)

In electronics, the Carey Foster bridge is a bridge circuit used to measure medium resistances, or to measure small differences between two large resistances. It was invented by Carey Foster as a variant on the Wheatstone bridge. He first described it in his 1872 paper "On a Modified Form of Wheatstone's Bridge, and Methods of Measuring Small Resistances" (Telegraph Engineer's Journal, 1872–1873, 1, 196).

Use

In the adjacent diagram, X and Y are resistances to be compared. P and Q are nearly equal resistances, forming the other half of the bridge. The bridge wire EF has a jockey contact D placed along it and is slid until the galvanometer G measures zero. The thick-bordered areas are thick copper busbars of very low resistance, to limit the influence on the measurement.

Place a known resistance in position Y.
Place the unknown resistance in position X.
Adjust the contact D along the bridge wire EF so as to null the galvanometer. This position (as a percentage of distance from E to F) is $ℓ 1$ .
Swap X and Y. Adjust D to the new null point. This position is $ℓ 2$ .
If the resistance of the wire per percentage is $σ$ , then the resistance difference is the resistance of the length of bridge wire between $ℓ 1$ and $ℓ 2$ :

X-Y=\sigma (\ell _{2}-\ell _{1})\,

To measure a low unknown resistance X, replace Y with a copper busbar that can be assumed to be of zero resistance.

In practical use, when the bridge is unbalanced, the galvanometer is shunted with a low resistance to avoid burning it out. It is only used at full sensitivity when the anticipated measurement is close to the null point.

To measure σ

To measure the unit resistance of the bridge wire EF, put a known resistance (e.g., a standard 1 ohm resistance) that is less than that of the wire as X, and a copper busbar of assumed zero resistance as Y.

Theory

Two resistances to be compared, X and Y, are connected in series with the bridge wire. Thus, considered as a Wheatstone bridge, the two resistances are X plus a length of bridge wire, and Y plus the remaining bridge wire. The two remaining arms are the nearly equal resistances P and Q, connected in the inner gaps of the bridge.

A standard Wheatstone bridge for comparison. Points A, B, C and D in both circuit diagrams correspond. X and Y correspond to R₁ and R₂, P and Q correspond to R₃ and R_X. Note that with the Carey Foster bridge, we are measuring R₁ rather than R_X.

Let $ℓ 1$ be the null point D on the bridge wire EF in percent. $α$ is the unknown left-side extra resistance EX and $β$ is the unknown right-side extra resistance FY, and $σ$ is the resistance per percent length of the bridge wire:

{P \over Q}={{X+\sigma (\ell _{1}+\alpha )} \over {Y+\sigma (100-\ell _{1}+\beta )}}

and add 1 to each side:

{P \over Q}+1={{X+Y+\sigma (100+\alpha +\beta )} \over {Y+\sigma (100-\ell _{1}+\beta )}}

(equation 1)

Now swap X and Y. $ℓ 2$ is the new null point reading in percent:

{P \over Q}={{Y+\sigma (\ell _{2}+\alpha )} \over {X+\sigma (100-\ell _{2}+\beta )}}

and add 1 to each side:

{P \over Q}+1={{X+Y+\sigma (100+\alpha +\beta )} \over {X+\sigma (100-\ell _{2}+\beta )}}

(equation 2)

Equations 1 and 2 have the same left-hand side and the same numerator on the right-hand side, meaning the denominator on the right-hand side must also be equal:

{\begin{aligned}&Y+\sigma (100-\ell _{1}+\beta )=X+\sigma (100-\ell _{2}+\beta )\\\Rightarrow {}&X-Y=\sigma (\ell _{2}-\ell _{1})\end{aligned}}

Thus: the difference between X and Y is the resistance of the bridge wire between $ℓ 1$ and $ℓ 2$ .

The bridge is most sensitive when P, Q, X and Y are all of comparable magnitude.

References

A. H. Fison (1919). "Obituary notices: .... George Carey Foster, 1835–1919; ..." J. Chem. Soc., Trans. 115: 412–427. doi:10.1039/CT9191500408.

v t e Bridge circuits
Resistance	Kelvin bridge Wheatstone bridge
Resistance–Capacitance	Schering bridge Wien bridge
General	Bridged T circuit Carey Foster bridge Fontana bridge Lattice filter Murray loop bridge Transformer ratio arm bridge
Inductance	Maxwell bridge Anderson's bridge Hay's bridge
Other	Diode bridge H-bridge

Read other articles:

Bendera Bermuda

Rasio bendera 1:2 Bendera Bermuda ini dipakai oleh pemerintahan sejak tanggal 4 Oktober 1910. Desainnya menggunakan lambang bendera Inggris dan lambang Bermuda. Tidak seperti bendera lainnya yang menggunakan lambang bendera Inggris, warna latar yang digunakan adalah merah, bukan biru (seperti contohnya bendera Australia dan Anguilla). Lihat pula Lambang Bermuda Artikel bertopik bendera ini adalah sebuah rintisan. Anda dapat membantu Wikipedia dengan mengembangkannya.lbs

Abortus pada sapi

Artikel ini sebatang kara, artinya tidak ada artikel lain yang memiliki pranala balik ke halaman ini.Bantulah menambah pranala ke artikel ini dari artikel yang berhubungan atau coba peralatan pencari pranala.Tag ini diberikan pada April 2016. Abortus pada sapi adalah ketidakmampuan fetus sapi untuk bertahan hidup sebelum waktunya dilahirkan, namun proses pembentukan organ pada fetus tersebut telah selesai.[1] Jika kebuntingan berakhir sebelum terjadinya organogenesis, prosesnya dinama...

Kartu kredit

Kartu kredit Sistem kartu kredit adalah suatu jenis penyelesaian transaksi ritel dan sistem kredit, yang namanya berasal dari kartu plastik yang diterbitkan kepada pengguna sistem tersebut. Kartu kredit adalah salah satu instrumen utang yang dikeluarkan oleh pihak bank serta memiliki nilai peminjaman yang harus dikembalikan ke bank penerbit dalam jangka waktu tertentu.[1] Kartu kredit biasanya mengenakan tingkat persentase tahunan yang lebih tinggi dibandingkan bentuk pinjaman konsume...

مقاطعة يونيون (كارولاينا الشمالية)

لمعانٍ أخرى، طالع مقاطعة يونيون (توضيح). مقاطعة يونيون الإحداثيات 34°59′N 80°32′W / 34.99°N 80.53°W / 34.99; -80.53 [1] تاريخ التأسيس 1842 سبب التسمية دمج تقسيم إداري البلد الولايات المتحدة[2][3] التقسيم الأعلى كارولاينا الشمالية العاص...

Panggilan tidak terjawab

Artikel ini perlu dikembangkan dari artikel terkait di Wikipedia bahasa Inggris. (Oktober 2023) klik [tampil] untuk melihat petunjuk sebelum menerjemahkan. Lihat versi terjemahan mesin dari artikel bahasa Inggris. Terjemahan mesin Google adalah titik awal yang berguna untuk terjemahan, tapi penerjemah harus merevisi kesalahan yang diperlukan dan meyakinkan bahwa hasil terjemahan tersebut akurat, bukan hanya salin-tempel teks hasil terjemahan mesin ke dalam Wikipedia bahasa Indonesia. Jan...

The Prison (film 2017)

The PrisonPoster promosiSutradaraNa HyunProduserChoi Ji-yoonSkenarioNa HyunPemeranHan Suk-kyuKim Rae-wonPenata musikBang Jun-seokSinematograferHong Jae-sikPenyuntingKim Chang-jooPerusahaanproduksiCuro HoldingsDistributorShowboxTanggal rilis 23 Maret 2017 (2017-03-23) Durasi125 menitNegaraKorea SelatanBahasaKoreaPendapatankotorUS$21,2 juta[1] The Prison (Hangul: 프리즌; RR: Peurijeun; lit. Prison) adalah sebuah film laga penjara Korea Selata...

Hawken and Vance Produce Exchange

Heritage-listed building in Sydney, Australia Hawken and Vance Produce ExchangeHawken and Vance Produce Exchange, 95–99 Sussex Street, SydneyLocation95–99 Sussex Street, Sydney, AustraliaCoordinates33°52′05″S 151°12′12″E / 33.8681°S 151.2033°E / -33.8681; 151.2033Architectural style(s)Victorian Free Classical New South Wales Heritage RegisterOfficial nameHawken & Vance Produce ExchangeTypeState heritage (built)Designated2 April 1999Reference no...

Élections législatives de 1924 dans l'Aisne

1919 1928 Élections législatives de 1924 dans l'Aisne 8 sièges de députés à la Chambre des députés 11 mai 1924 Type d’élection Élections législatives Corps électoral et résultats Population 421 515 Votants 116 529 86,31 % 22,4 Bloc national Liste PRDFédération républicaineALP Voix 39 594 34,60 %  1 Députés élus 5 1 Cartel des gauches Liste Parti radicalSFIO Voix 35 639 31,14 %  27...

Hubungan Mali dengan Tiongkok

Hubungan Tiongkok-Mali Tiongkok Mali Kedubes Mali di Tiongkok Hubungan Tiongkok–Mali merujuk kepada hubungan bilateral antara Tiongkok dan Mali. Republik Rakyat Tiongkok mendirikan hubungan diplomatik dengan Republik Mali pada 25 Oktober 1960.[1] Referensi ^ http://www.china.org.cn/english/features/focac/183436.htm lbs Hubungan luar negeri TiongkokHubungan bilateralAfrika Afrika Selatan Afrika Tengah Aljazair Angola Benin Botswana Burkina Faso Burundi Chad Eritrea Etiopia Gabon Gam...

コルク

この記事は検証可能な参考文献や出典が全く示されていないか、不十分です。出典を追加して記事の信頼性向上にご協力ください。（このテンプレートの使い方）出典検索?: コルク – ニュース · 書籍 · スカラー · CiNii · J-STAGE · NDL · dlib.jp · ジャパンサーチ · TWL（2017年4月）コルクを打ち抜いて作った瓶の栓コルク（木栓、�...

Cotton Bowl (stadion)

Untuk stadion sepak bola Amerika di Dallas, Texas, Amerika Serikat, lihat Cotton Bowl (disambiguasi). Stadion Cotton BowlThe House That Doak BuiltWest grandstand main entrance in 2016Nama lamaStadion Fair Park(1930–1936)Alamat1300 Robert Cullum Blvd.LokasiDallas, Texas, Amerika SerikatPemilikPemerintah Kota DallasKapasitas92,100[1]Rekor kehadiran96,009[2]PermukaanRumput alami(1930–1969, dari 1994)AstroTurf (1970–1993)KonstruksiMulai pembangunan1930[3]Dib...

Новотитаровское сельское поселение

Сельское поселение России (МО 2-го уровня)Новотитаровское сельское поселение Флаг[d] Герб 45°14′09″ с. ш. 38°58′16″ в. д.HGЯO Страна Россия Субъект РФ Краснодарский край Район Динской Включает 4 населённых пункта Адм. центр Новотитаровская Глава сельского пос�...

Taiwanese rock

This article does not cite any sources. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed.Find sources: Taiwanese rock – news · newspapers · books · scholar · JSTOR (February 2017) (Learn how and when to remove this message) The topic of this article may not meet Wikipedia's general notability guideline. Please help to demonstrate the notability of the topic by citing reliable sec...

بطولة كرة القدم الألمانية 1929

بطولة كرة القدم الألمانية 1929 تفاصيل الموسم بطولة كرة القدم الألمانية [لغات أخرى]‏ النسخة 22 البلد الرايخ الألماني التاريخ بداية:9 يونيو 1929 نهاية:28 يوليو 1929 المنظم الاتحاد الألماني لكرة القدم البطل غرويتر فورت مباريات ملعوبة 16 عدد المشارك�...

Beeban Kidron

British film director and politician (born 1961) The Right HonourableThe Baroness KidronOBEOfficial portrait, 2024Member of the House of LordsLord TemporalIncumbentAssumed office 26 June 2012Life peerage Personal detailsBornBeeban Tania Kidron (1961-05-02) 2 May 1961 (age 63)North London, EnglandSpouse Lee Hall (m. 2003)Children2ParentMichael Kidron (father)Alma materNational Film SchoolOccupationFilm director, producer, campaigner Beeban Tania Kidron, ...

Перспектива

У этого термина существуют и другие значения, см. Перспектива (значения). Перспекти́ва (фр. perspective, итал. prospettiva, от лат. perspicere — ясно видеть, смотреть сквозь, проникать взором, пристально рассматривать) — ясное ви́дение, панорама, взгляд вдаль, картина широког�...

User talk:Cunado19

Please leave a message at User talk:Cuñado Archives My first archive, I'm so proud. Archive1 19 messages from 21 Jun 2005 to 20 September 2005 Wow, I'm on number two. Archive2 28 messages from 7 October 2005 to 10 February 2006 I can't believe I've been doing this so long! Archive3 27 messages from 12 February 2006 to 25 March 2006 I'm addicted to Wikipedia. Archive4 28 messages from 6 April 2006 to 7 July 2006 I'll give up someday. Archive5 28 messages from 14 July 2006 to 27 November 2006 ...

Assyrians in Turkey

Ethnic group in the Republic of Turkey Ethnic group Turkish Assyriansܣܘܪܝܝܐ ܕܛܘܪܩܝܐ (Syriac) Turkish Assyrian Christians in Cevizağacı, BeytüşşebapTotal population25,000[1]~600,000 (diaspora)Regions with significant populationsMainly Istanbul Cities of Hakkâri, Mardin and Yüksekova Southeastern Anatolia Region (historically)LanguagesSuret, Surayt, TurkishReligionSyriac Christianity Assyrians in Turkey (Turkish: Türkiye Süryanileri, Syriac: ܣܘܪܝܝܐ ܕܛܘܪܩ...

Genzebe Dibaba

Artikel ini sebatang kara, artinya tidak ada artikel lain yang memiliki pranala balik ke halaman ini.Bantulah menambah pranala ke artikel ini dari artikel yang berhubungan atau coba peralatan pencari pranala.Tag ini diberikan pada November 2022. Genzebe DibabaGenzebe Dibaba in 2016Informasi pribadiKewarganegaraanEtiopiaLahir8 Februari 1991 (umur 33)[1]Bekoji, Etiopia[1]Tinggi168 cm (5 ft 6 in)[1]Berat52 kg (115 pon)[1] OlahragaNega...

University of California, Irvine

Public university in Irvine, California University of California, IrvineMottoFiat lux (Latin)Motto in EnglishLet there be lightTypePublic land-grant research universityEstablishedOctober 4, 1965; 58 years ago (1965-10-04)[1]Parent institutionUniversity of CaliforniaAccreditationWSCUCAcademic affiliationsAAUURASpace-grantEndowment$1.3 billion (2022)[2]ChancellorHoward Gillman[3]ProvostHal Stern[4]Academic staff5,596 (2019)[5]Admini...

African-American family structure

/profillengkap.com/index.php/article/Eric Zehr

/profillengkap.com/index.php/article/Sünt-Hasardag Sanctuary

Bertuccio Valiero

Bukal, Bukal, Buol

ITC Cempaka Mas Mega Grosir

Manyingsal, Cipunagara, Subang

غثيان وقيء بعد العملية الجراحية

Emmett Till and Mamie Till-Mobley National Monument

Bandar Udara Internasional O'Hare

E. D. Hill

Ignatius Sandyawan Sumardi