Lektion 1 Sidan 2 av 5
© Pentronic AB 2017-01-19 ------However, the thermometer had no real practical use until 1714, when the German physicist Daniel Gabriel Fahrenheit developed a temperature scale that made it possible to take comparative measurements. He is also considered to be the inventor of the mercury thermometer as it is today – that is, mercury inside a closed glass tube.
It is worth pointing out that the glass thermometers containing mercury that may still be in use are being used by special exemption. Mercury is a stable substance but it becomes dangerous out in the environment. Today we use other liquids such as coloured alcohol.
The temperature scales
Fahrenheit Fahrenheit created a 100-degree scale in which zero degrees was the temperature of a mixture of sal ammoniac and snow – the coldest he could achieve in his laboratory in Danzig.
As the upper fixed point he used the internal body temperature of a healthy human being and gave it the value of 100°F. In degrees Celsius this scale corresponds approximately to the range of -18 to +37 degrees.
With this issue Pentronic begins its training in Becausetemperature it can be awkwardmeasurement to achieve .the We upper will fixed start point , he apparently introduced the more practical fixed points of +32°F and +96°F, which were respectively the freezing point of lesson 1 with a historical review and then continuewater and with the temperaturethermodynamics, of a human being’sheat armpittransfer. and quality assurance with calibration. Only after that will we move on to temperature sensors – primarily thermocouples and Pt100s.Fahrenheit’s scale was later extended to the boiling point of water, which was assigned the temperature value of +212°F.
212 °F, boiling point of water
LESSON 1 THE NATURE AND
HISTORY OF TEMPERATURE 100 °F, internal body temperature of a human
96 °F, temperature of a human armpit
TEMPERATURE – HEAT also developed simple scales, which
Temperature does not exist. It is a included the divisions of 40 and 80 32 °F, freezing point of water theoretical model constructed so that degrees between the “fixed points” humans can measure, compare and of the high summer temperature and 0 °F, snow/sal ammoniac mixture understand changes of kinetic energy the low winter temperature. among a body’s smallest compo However, the thermometer had no nents such as atoms and molecules. real practical use until 1714, when Fahrenheit’s mercury-in-glass thermo- In contrast, heat does exist and the German physicistFahrenheit Daniel Gabriel’s mercury -imetern-glas withs thermometer the reference with points the reference that points that were apparently is described as being the amount of Fahrenheit developedused a temperature. were apparently used. kinetic energy inside a body. From scale that made it possible to take this it follows that everything above comparative measurements.Anders HeCelsius is absolute zero (-273.15°C) is heat. also considered to beAt the the inventor same time, people Becausewere considering it can be having awkward a scale to with more natural divisions But this definition leads to peculiar of the mercury thermometerwhereby as 0 degreesit wasachieve defined the as upper the melting fixed pointpoint, of heice and 100 as the boiling point of effects. For example, an iceberg is today – that is, mercurywater. inside We know a that evenapparently before 1737introduced Linneaus the wasmore using this scale, which was later contains more heat than a cup of closed glass tube. named after the Swedishpractical astronomer fixed Anderspoints Celsius.of +32°F and coffee, because the iceberg contains It is worth pointing out that the +96°F, which were respectively the a greater amount of energy. glass thermometers containing freezing point of water and the tem Anyone who puts a finger on the mercury that may still be in use are perature of a human being’s armpit. iceberg and the coffee respectively being used by special exemption. Fahrenheit’s scale was later ex experiences the opposite. What Mercury is a stable substance but tended to the boiling point of water, we then feel is the heat, the kinetic it becomes dangerous out in the which was assigned the temperature energy, at a given point. Temper environment. Today we use other value of +212°F. ature is our tool for describing this liquids such as coloured alcohol. experience in a comparable and ANDERS CELSIUS reproducible way. The coffee feels At the same time, people were hotter than the iceberg because it THE TEMPERATURE SCALES considering having a scale with more has a higher temperature. natural divisions whereby 0 degrees FAHRENHEIT was defined as the melting point of THE PIONEERS Fahrenheit created a 100-degree ice and 100 as the boiling point of The thermometer was invented at the scale in which zero degrees was water. We know that even before beginning of the 17th century by the the temperature of a mixture of sal 1737 Linneaus was using this scale, Italians Galileo and Santorio at the ammoniac and snow – the coldest which was later named after the Accademia del Cimento in Florence he could achieve in his laboratory in Swedish astronomer Anders Celsius. and by the Dutchman Drebbel. The Danzig. In 1742 Celsius launched the first thermometer consisted of a As the upper fixed point he used scale in reverse order, arguing that spiral-shaped glass tube filled with the internal body temperature of a water should boil at 0 degrees and alcohol. The tube was not closed healthy human being and gave it the freeze at 100. Not until eight years and therefore the instrument also value of 100°F. In degrees Celsius later was the scale reversed by his measured the air pressure at the this scale corresponds approximately successor as professor at Uppsala same time. The academy in Florence to the range of -18 to +37 degrees. University, the mathematician Mårten
A finger feels how the heat energy (also called thermal energy) moves (see the ar- Anders Celsius. row) in or out depending on whether the temperature of the object being touched is higher or lower than the finger’s. Strömer. As an interesting aside, it p V = R T where Temperature is a measurement is worth mentioningLektion 1 that asLektion early 1 as Sidan 3 av 5 Sidan 3 av 5 of what is regarded as the “anima p = the gas pressure © Pentronic AB © Pentronic1743, AB Professor Christin in Lyon had 2017-01-19 2017-01-19 tion” or movements of the smallest ------V = the enclosed ------volume (in moles) In 1742 Celsius launchedIn 1742built the Celsius thescale firstlaunched in reverse mercury the order, scale arguing thermometerin reverse that order,water arguingshould boil thatR at water= 0 the should universal boil at 0gas constant components of matter such as atoms degrees and freezedegrees at with100. andNot the freezeuntil Celsius eight at 100. years scaleNot later until was“the eight the rightyears scale later reversedway was theby hisscaleT = reversedthe absolute by his temperature of the gas and molecules. From experience we successor as professorsuccessorround”. at Uppsala as professor University at Uppsala, the mathematician University, theMårten mathematician Strömer. As Mårten an Strömer. As an know that increasing thermal (heat) interesting aside, itinteresting is worth mentioning aside, it is that worth as mentioningearly as 1743, that P asrofessor early as Christin 1743, Pinrofessor Lyon had Christin in Lyon had energy leads to higher temperatures, built the first mercurybuilt thermometer the first mercury with thethermometer Celsius scale with “the the rightCelsius way scale round” “the. right way round”. and as a rule requires that matter 0 °, boiling point of water 0 ° , boiling point of water 100 °C, boiling point of100 water °C, boiling point of water expands in volume. (Compare with the ideal gas law!) It is therefore not
Diagram, left: The 100-degree temperature unreasonable to assume that the scale as used by Anders Celsius. Right: His lowest temperature is to be found successor as professor at Uppsala, Mårten where the so-called animation or Strömer, reversed the scale so that its values increase with the energy level just as we are movement has stopped. This occurs used to seeing it today. at absolute zero, 0 K. To maintain agreement with the
already accepted Celsius scale, 100 °, freezing point of100 water °, freezing point of water 0 °C, freezing point of 0water °C, freezing point of water it was decided that 1°C = 1 K = 1/273.16 of the thermodynamic tem This law is the starting point of perature at the triple point of water. Avogadro’s temperature scale, We can say that thermodynamic Diagram, left: The Diagram100-RÉAUMURdegree, left temperatur: The 100-degreee scale temperaturas used bye Anders scale as Celsius. used by Right Anderswhich: His Celsius. begins Right at: His absolute zero. temperature scale is defined by one successor as professorsuccessorDuring at Uppsala, as professorthe Mårten same at Strömer, Uppsala, period, reversed Mårten the Strömer,theFrench scale reversedso that its theToday values scale soabsolute that its values zero is defined as increase with the energyincrease level with just the as energy we are level used just to seeingas we are it today used. to seeing it today. fixed point and one fictive zero point man Réaumur developed his own -273.15°C. The problem with the gas – absolute zero. The fixed point is the Réaumur Réaumurscale. He also began with the thermometer is that it assumes that triple point of water, which is a state During the same perDuringiodfreezing, the the Frenchman same and period Réaumurboiling, the Frenchman developedpoints Réaumur of his water own developed scale. He alsohisso own began-called scale. He“ideal also began gas” exists. with the freezing andwith boiling the freezing points ofand water boiling but pointshe divided of water his scalebut he into divided 80°R, his because scale into his 80°R, because his of equilibrium between water’s three favourite mixture offavourite waterbut and mixturehe alcohol divided of expandedwater his and scaleitselfalcohol from intoexpanded 1,000 80°R, till itself 1,080 from units 1, 000of volume till 1,080 units of volume phases of solid, liquid and gas. In this between the fixed pointsbetweenbecause. the fixed his points favourite. mixture of THERMODYNAMIC SCALE condition, water assumes a highly water and alcohol expanded itself At the same time, other research stable and difficult-to-disrupt state of Heat was a substanceHeat was a substance fromth 1,000 till 1,080th units of volume was also being done into the field Only near the end Onlyof the near 18 thecentury end ofdid the researchers 18 century begin did researchersto understand begin the natureto understand of heat. the nature of heat. equilibrium, which has been assigned Until then, heat wasUntil believedbetween then, heatto consist was the believed of fixed a particular to points.consist substance of a particular called “ caloricsubstance”. of called energy. “caloric The”. Frenchman Carnot, the theoretical temperature value the German Mayer and the Briton of precisely 0.01°C. Note that in It was the AmericanIt -wasbornHEAT the Briton American WASCount -Rumfordborn A SUBSTANCE Briton who Count tracked Rumford down whothe explanation tracked downJoule by the explanationwere some by of those who made demonstrating thatdemonstrating a specific amount that ofa specificice weighed amount the ofsame ice weighedwhen it was the samemelted. when The it was melted. The practical experiments such precision Lektion 1 Sidan 4 av 5 caloric theory couldcaloric therebyOnly theory be near dismissed could the thereby . endHe alsobe of dismissed succeeded the 18th. He in centuryalsogetting succeeded water to boilinmajor getting by contributionswater to boil by to explaining the cannot be achieved. However, it is boring a blunt drill inboringto a pie a bluntce of drillmetal in.to Rumford a piece ofwas metal convinced. Rumford that was the convincedmovement that of the the movement of the did researchers begin to understand © Pentronicconnection AB between different forms of relatively simple to 2017achieve-01-19 the triple drill was transformeddrill into thewas heat transformednature vibrations of into inheat. the heat metal’ Untilvibrationss atoms then, in. the heat metal’ s atoms-.------energy. Joule’s experiments included point of water with a------measurement V = the enclosed volume (in moles) The ideal gas lawThe was ideal believed gas law to consist of a parti determining the amount of mechani uncertainty of less than ±0.001°C. th th R = the universal gas constant At the beginning ofAt the thecular 19 beginning century substance ofthe the ideal 19 gas calledcentury law was the“caloric”. developedideal gas law from was Boyle’s developed callaw byeffort from Boyle’s required law by to raise the tem Absolute zero cannot be fully several well-knownseveral researchers, Itwell was-known including the res Americanearchers, the Frenchmen including-born Charles the Briton Frenchmen and Gay -Lussac Charles perature and and the Gay T-ofLussac = 1the gram absoluteand the of watertemperatur by e1°C. of the gas Italian Avogadro. TheItalian law Avogadro. states: The law states: Fenela Childs 2017-2-14 Fenela13:19 Childs 2017-2-14 13:19achieved. Empirically, it has been Count Rumford who tracked down This lawThe is researchthe startingKommentar resulted point [1]: of börAvogadro inha Kommentaren the bindessträck laws’s temperatur [1]: bör ha en bindessträckeestablished scale, which begins at -273.15°C. at absolute zero.At även på svenska! även på svenska! p V = R T p V the= R T explanation by demonstrating Todayof thermodynamics. absolute zero is defined In about as -273.15°C. 1850 The problemHelsinki with the University gas thermometer of Technol is that it that a specific amount of iceweighed assumesthe Briton that so Kelvin-called defined “ideal gas” temper exists. ature where p = thewhere gas pressure p = the gas pressure ogy researchers study low tem the same when it was melted. The in accordance with these laws. Today peratures and in their experiments caloric theory could thereby be Thermodynamicwe still do not scaleknow what temper have apparently come down to dismissed. He also succeeded in Atature the same really time is., other Instead, research we was use also the being done into the field of energy. The Frenchman Carnot, the German Mayer and the Briton nKJoule (nanokelvin were some of =those 10- who9) away made from getting water to boil by boring a blunt majortheories contributions of thermodynamics to explaining the connectionbecause betweenabsolute different zero.forms of energy. Joule’s drill into a piece of metal. Rumford expetheyriment agrees included sufficiently determining well the with amount of mechanicalThe effort Kelvin required scale to raise is scientifi the was convinced that the movement temperatureexperimental of 1 gram tests. of water by 1°C. cally and mathematically correct. of the drill was transformed into heat Unfortunately it is not useable in vibrations in the metal’s atoms. Thermodynamic The research resulted in temperature (K) practice becausethe laws ofthe measure ments canthermodynamics. only be taken In with gas THE IDEAL GAS LAW thermometersabout containing 1850 the Briton ideal gas. At the beginning of the 19th century And ideal gasKelvin does defined not exist. the ideal gas law was developed If you wouldtemperatur like toe in discover even from Boyle’s law by several well- more aboutaccordance temperature with thesemeasu re known researchers, including the 273.16 laws. Today we still do ment,not Pentronic know what offers cour Frenchmen Charles and Gay-Lussac ses in “Traceable temper and the Italian Avogadro. The law temperature really is. 0 atureInstead, measurement” we use the in states: 0 Triple point of water Energy level Västerviktheories of or at your own thermodynamicspremises if required. TheThe thermodynamic scale scale is defined is defined by two points:by two the points:triple because they agree the triple point of water (solid circle) and absolute zero sufficientlyFor more well informationwith point of water (solid circle) and absolute zero (empty circle), visit www.pentronic.se (emptywhich cannot circle), be achievedwhich cannot. be achieved. experimental tests.
Temperature is a measurement of what is regarded as the “animation” or movements of the smallest components of matter such as atoms and molecules. From experience we know that PENTRONIC’S PRODUCTS AND SERVICESincreasing thermal (heat) energy leads to higher temperatures, andPENTRONIC as a rule requires NEWS 2017-1that • VOL. 9 matter expands in volume. (Compare with the ideal gas law!) It is therefore not unreasonable Temperature sensors Connectorsto assume and thatcables the lowest temperature is to be found where the so-called animation or movement has stopped. This occurs at absolute zero, 0 K. Temperature transmitters IR-pyrometers Temperature indicators TemperatureTo maintain controllers agreement with the already accepted Celsius scale, it was decided that 1°C = 1 K = 1/273.16 of the thermodynamic temperature at the triple point Bergsliden of water. 1, SE-593 96 Västervik Dataloggers Temperature calibration equipment Tel. 0490-25 85 00, Fax. 0490-237 66 Temperature calibration services Training courses in temperature www.pentronic.se We can say that thermodynamic temperature scale is defined by one fixed point and one Moisture and thickness monitors Flowmetersfictive zero point – absolute zero. The fixed point is the triple point of water, which is a state GFM Glass flow meters Electroof -equilibriumoptical test betweensystems water’s three phases of solid, liquid and gas. In this condition,Subscribe water to Pentronic News assumes a highly stable and difficult-to-disrupt state of equilibrium, which hasat our been website assigned www.pentronic.se the theoretical temperature value of precisely 0.01°C. Note that in practical experiments such precision cannot be achieved. However, it is relatively simple to achieve the triple point of water with a measurement uncertainty of less than ±0.001°C.