Uma silinganisa izinhlobo ezahlukene zama-thermometer, isibonelo i-mercury thermometer kanye ne-alcohol thermometer, izikali zama-thermometer womabili ziyafana kuphela ku-0 o C (noma ku-32 o F) kanye no-100 o C (noma ku-212 o F). Uma sisebenzisa womabili ama-thermometer ukukala izinga lokushisa lomoya, izinombolo eziboniswa yi-thermometer ngayinye ngeke zifane ngempela. Kungenzeka ukuthi i -mercury thermometer ikhombisa u-48 o C, kanti i-alcohol thermometer ikhombisa u-46 o C. Lokhu kungenxa yokuthi izinga lokukhula kwe-mercury kanye ne-alcohol lihlukile. Ngokufanayo nezinye izinhlobo zama-thermometer, njenge-bimetallic thermometers, njll. Isikali sokushisa esinqunywa ngale ndlela sincike kakhulu ezimpahleni zezinto ezisetshenziswayo.
Ngenxa yokuthi isikali sokushisa esisetshenziswa kusetshenziswa i-thermometer evamile sinezinkinga zaso, sidinga i-thermometer ejwayelekile. I-thermometer ejwayelekile isenza sikwazi ukusungula isikali sokushisa esinembile ngaphandle kokuthembela ezimpahleni zezinto.
I-thermometer ecishe iphelele yi - thermometer yegesi engumthamo oqhubekayo . Isimiso sokusebenza kwe-thermometer yegesi engumthamo oqhubekayo yile: Umthamo wegesi ugcinwa ungaguquki, noma ungaguquki. Njengoba izinga lokushisa likhuphuka, ingcindezi yegesi nayo iyanda.
Ngaphakathi kwamapayipi 1 no-2 kukhona i-mercury. Umthamo wegesi ugcinwa ungaguquki ngokuphakamisa noma ukwehlisa ipayipi 2 ukuze izinga le-mercury epayipini 1 lihlale lisesibonini sokubhekisela. Uma izinga lokushisa likhuphuka, umfutho wegesi epayipini nawo uyakhuphuka. Ngakho-ke, ipayipi 2 kumele liphakanyiswe phezulu ukuze umthamo wegesi uhlale ungaguquki. Umfutho wegesi unganqunywa ngokufunda ukuphakama kwekholomu ye-mercury (h) epayipini 2. Uma usebenzisa indlela yesandla, khumbula nje ukuthi ikholomu ye-mercury engu-760 mm ukuphakama = i-atm eyi-1 (umkhathi ongu-1) wokucindezela. Kuma-thermometer egesi aguqukile aguqukile kakade kukhona ikhawunta yokucindezela. Isitsha esiqukethe igesi naso senzelwe ukuthi igesi ihlale inomthamo ongaguquki. Ngakho-ke okulinganiselwe ushintsho kuphela ekucindezelweni.
Ukuze silinganise i-thermometer yegesi engumthamo oqhubekayo, singalinganisa ingcindezi yegesi emazingeni okushisa amabili. Isibonelo, ake sisebenzise amazinga okushisa e-ice point kanye ne-vapor point. Ama-thermometer egesi angumthamo oqhubekayo alinganiswa emazingeni okushisa angu-1 atm. Izinyathelo zokulinganisa i-thermometer yilezi ezilandelayo.
Okokuqala, isilinda segesi sifakwa esitsheni esiqukethe iqhwa namanzi. Umthamo wegesi ugcinwa ungaguquki, ngakho-ke ipayipi 2 kumele lehliswe ukuze izinga le-mercury epayipini 1 lihlale endaweni yokubhekisela. Uma umthamo wegesi ungakashintshi, bhala phansi ukuphakama kwekholomu ye-mercury (h) epayipini 2. Sebenzisa i-h ukuze ubale ingcindezi. Uma usebenzisa i-thermometer yegesi yevolumu engaguquki eyinkimbinkimbi, isilinda esigcwele igesi sicwiliswa ngqo esitsheni esiqukethe iqhwa namanzi. Sekuvele kukhona i-pressure gauge. Qopha ingcindezi yegesi (ake sithi lokhu kuyingcindezi 1 noma i-P 1 )
Okwesibili, Isilinda segesi sifakwa esitsheni esinamanzi afudunyezwayo. Ukuze kugcinwe ivolumu yegesi engaguquki, ipayipi 2 liyaphakanyiswa ukuze izinga le-mercury epayipini 1 lihlale endaweni yokubhekisela. Uma ivolumu yegesi ingashintshi, bhala phansi ukuphakama kwekholomu yamanzi. 
i-mercury (h) epayipini 2. Sebenzisa i-h ukubala ingcindezi yegesi (ake sithi lokhu kuyingcindezi 2 noma i-P2)
Okwesithathu , dala igrafu echaza ubudlelwano phakathi kwengcindezi kanye nokushisa. Bheka isibonelo esingezansi.
I-P 1 ingcindezi yegesi ekushiseni kwephuzu leqhwa (0 o C) kanti i-P 2 ingcindezi yegesi ekushiseni kwephuzu lomhwamuko (100 o C). Dweba umugqa oxhumanisa indawo yokuhlangana kwe-P 1 no-0 o C kanye nendawo yokuhlangana kwe-P 2 no-100 o C. Ngokubhekisela kugrafu, yize sazi ingcindezi yegesi kuphela, izinga lokushisa lingaziwa kalula futhi libikezelwe.
Isikali sikaKelvin
Uma umugqa oqondile kugrafu engenhla udwetshwa ukuze uhlangane ne-axis ye-To C , khona-ke lapho ingcindezi yegesi = 0, izinga lokushisa legesi = -273,15 o C. Mhlawumbe sicabanga ukuthi izinga lokushisa legesi kungcindezi engu-0 liyahlukahluka, kuye ngohlobo lwegesi ku-thermometer yegesi yevolumu engaguquki. Ngokusekelwe ekuhlolweni, noma ngabe uhlobo lwegesi luhlukile, lapho ingcindezi yegesi iba yi-zero, izinga lokushisa lihlala liyi-273,15 o C. Ngakho-ke, singasebenzisa leli zinga lokushisa njengesikali sokushisa esijwayelekile (esaziwa nangokuthi izinga lokushisa eliyi-zero eliphelele). Leli zinga lokushisa eliyi-zero eliphelele laziwa njengesiteketiso sesikali esiphelele noma isikali sikaKelvin. UKelvin igama likaLord Kelvin ongasekho (1824-1907), owayengusosayensi waseBrithani.
Kulesi sikali, izinga lokushisa livezwa ku-Kelvin (K), hhayi kuma-degrees ka-Kelvin (oK). Isikhawu esiphakathi kwamadigri siyafana nesikalini seCelsius, kodwa inani lika-zero lishintshelwa ku-0 K. Ngakho-ke u-0 K = -273,15 oC kanye no-273,15 K = 0 oC. Izinga lokushisa esikalini se-Celsius lingaguqulwa libe isikali se-Kelvin ngokungeza u-273,15. Ngokufanayo, izinga lokushisa esikalini se-Kelvin lingaguqulwa libe isikali se-Celsius ngokususa u-273,15.
T (K) = T (oC) + 273,15
T (oC) = T (K) – 273,15
Isibonelo sombuzo 1.40 oC = …. K
T(K) = T(C) + 273
T = 20 + 273
T = 293 K
Isibonelo sombuzo 2. 80 o F = …. K
