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74-663: The TI-82 is a graphing calculator made by Texas Instruments . The TI-82 was designed in 1993 as an upgraded version of and replacement for the TI-81 . It was the direct predecessor of the TI-83 . It shares with the TI-85 a 6  MHz Zilog Z80 microprocessor . Like the TI-81, the TI-82 features a 96×64 pixel display, and the core feature set of the TI-81 with many new features. The TI-82

148-425: A platinum resistance thermometer, so these two will disagree slightly at around 50 °C. There may be other causes due to imperfections in the instrument, e.g. in a liquid-in-glass thermometer if the capillary tube varies in diameter. For many purposes reproducibility is important. That is, does the same thermometer give the same reading for the same temperature (or do replacement or multiple thermometers give

222-559: A temperature scale which now (slightly adjusted) bears his name . In 1742, Anders Celsius (1701–1744) proposed a scale with zero at the boiling point and 100 degrees at the freezing point of water, though the scale which now bears his name has them the other way around. French entomologist René Antoine Ferchault de Réaumur invented an alcohol thermometer and, temperature scale in 1730, that ultimately proved to be less reliable than Fahrenheit's mercury thermometer. The first physician to use thermometer measurements in clinical practice

296-414: A closed system, the final state of the system is never colder than the initial state; except for phase changes with latent heat, it is hotter than the initial state. There are several principles on which empirical thermometers are built, as listed in the section of this article entitled "Primary and secondary thermometers". Several such principles are essentially based on the constitutive relation between

370-653: A computer algebra system are called symbolic or CAS calculators. Many graphing calculators can be attached to devices like electronic thermometers , pH gauges, weather instruments, decibel and light meters , accelerometers , and other sensors and therefore function as data loggers , as well as WiFi or other communication modules for monitoring, polling and interaction with the teacher. Student laboratory exercises with data from such devices enhances learning of math, especially statistics and mechanics. Since graphing calculators are typically user-programmable, they are also widely used for utilities and calculator gaming , with

444-475: A computer can be programmed in assembly language and machine code, although on some calculators this is only possible through using exploits. The most common assembly and machine languages are for TMS9900 , SH-3 , Zilog Z80 , and various Motorola chips (e.g. a modified 68000 ) which serve as the main processors of the machines although many (not all) are modified to some extent from their use elsewhere. Some manufacturers do not document and even mildly discourage

518-447: A constant volume air thermometer. Constant volume thermometers do not provide a way to avoid the problem of anomalous behaviour like that of water at approximately 4 °C. Planck's law very accurately quantitatively describes the power spectral density of electromagnetic radiation, inside a rigid walled cavity in a body made of material that is completely opaque and poorly reflective, when it has reached thermodynamic equilibrium, as

592-534: A coordinate manifold of material behaviour. The points L {\displaystyle L} of the manifold M {\displaystyle M} are called 'hotness levels', and M {\displaystyle M} is called the 'universal hotness manifold'." To this information there needs to be added a sense of greater hotness; this sense can be had, independently of calorimetry , of thermodynamics , and of properties of particular materials, from Wien's displacement law of thermal radiation :

666-756: A dedicated keyboard, they are mostly preferred only by high school students. However, for developers and advanced users like researchers, analysts and gamers, third-party software development involving firmware modifications, whether for powerful gaming or exploiting capabilities beyond the published data sheet and programming language, is a contentious issue with manufacturers and education authorities as it might incite unfair calculator use during standardized high school and college tests where these devices are targeted. Most graphing calculators, as well as some non-graphing scientific calculators and programmer's calculators can be programmed to automate complex and frequently used series of calculations and those inaccessible from

740-439: A digital display or input to a computer. Thermometers may be described as empirical or absolute. Absolute thermometers are calibrated numerically by the thermodynamic absolute temperature scale. Empirical thermometers are not in general necessarily in exact agreement with absolute thermometers as to their numerical scale readings, but to qualify as thermometers at all they must agree with absolute thermometers and with each other in

814-432: A function of absolute thermodynamic temperature alone. A small enough hole in the wall of the cavity emits near enough blackbody radiation of which the spectral radiance can be precisely measured. The walls of the cavity, provided they are completely opaque and poorly reflective, can be of any material indifferently. This provides a well-reproducible absolute thermometer over a very wide range of temperatures, able to measure

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888-562: A graphical string of single byte characters but retain the two byte character in the program memory. Many graphical calculators work much like computers and use versions of 7-bit, 8-bit or 9-bit ASCII-derived character sets or even UTF-8 and Unicode . Many of them have a tool similar to the character map on Windows. They also have BASIC like functions such as chr$ , chr, char, asc, and so on, which sometimes may be more Pascal or C like. One example may be use of ord , as in Pascal , instead of

962-698: A large feature set—approaching that of BASIC as found in computers—including character and string manipulation, advanced conditional and branching statements, sound, graphics, and more including, of course, the huge spectrum of mathematical, string, bit-manipulation, number base, I/O, and graphics functions built into the machine. Languages for programming calculators fall into all of the main groups, i.e. machine code, low-level, mid-level, high-level languages for systems and application programming, scripting, macro, and glue languages, procedural, functional, imperative &. object-oriented programming can be achieved in some cases. Most calculators capable to being connected to

1036-399: A medically accurate body temperature. Traditional thermometers were all non-registering thermometers. That is, the thermometer did not hold the temperature reading after it was moved to a place with a different temperature. Determining the temperature of a pot of hot liquid required the user to leave the thermometer in the hot liquid until after reading it. If the non-registering thermometer

1110-501: A newline character). For a system as slow as a graphing calculator, this is too inefficient for an interpreted language . To increase program speed and coding efficiency, the above line of code would be only three characters. "Disp_" as a single character, "[A]" as a single character, and a newline character. This normally means that single byte chars will query the standard ASCII chart while two byte chars (the Disp_ for example) will build

1184-405: A platinum resistance thermometer with a digital display to 0.1 °C (its precision) which has been calibrated at 5 points against national standards (−18, 0, 40, 70, 100 °C) and which is certified to an accuracy of ±0.2 °C. According to British Standards , correctly calibrated, used and maintained liquid-in-glass thermometers can achieve a measurement uncertainty of ±0.01 °C in

1258-531: A recipe for building a "Fountain which trickles by the Action of the Sun's Rays," a more elaborate version of Philo's pneumatic experiment but which worked on the same principle of heating and cooling air to move water around. Translations of the ancient work Pneumatics were introduced to late 16th century Italy and studied by many, including Galileo Galilei , who had read it by 1594. The Roman Greek physician Galen

1332-512: A scale of 8 degrees. The word comes from the Greek words θερμός , thermos , meaning "hot" and μέτρον, metron , meaning "measure". The above instruments suffered from the disadvantage that they were also barometers , i.e. sensitive to air pressure. In 1629, Joseph Solomon Delmedigo , a student of Galileo and Santorio in Padua, published what is apparently the first description and illustration of

1406-426: A sealed liquid-in-glass thermometer. It is described as having a bulb at the bottom of a sealed tube partially filled with brandy. The tube had a numbered scale. Delmedigo did not claim to have invented this instrument. Nor did he name anyone else as its inventor. In about 1654, Ferdinando II de' Medici, Grand Duke of Tuscany (1610–1670) did produce such an instrument, the first modern-style thermometer, dependent on

1480-492: A significant boost in interest in the programmability of the calculator, as the use of assembly language (as opposed to Texas Instruments' own TI-BASIC ) enabled significantly more performance and flexibility with the programs able to be used on the calculator. Carried over from the TI-81 is the TI-82's power source – four AAA batteries and one CR1616 or CR1620 lithium backup battery (to ensure programs stored in RAM persist when

1554-506: A sizable body of user-created game software on most popular platforms. The ability to create games and utilities has spurred the creation of calculator application sites (e.g., Cemetech ) which, in some cases, may offer programs created using calculators' assembly language . Even though handheld gaming devices fall in a similar price range, graphing calculators offer superior math programming capability for math based games. However ,due to poor display resolution, slow processor speed and lack of

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1628-435: A thermometric material must have three properties: (1) Its heating and cooling must be rapid. That is to say, when a quantity of heat enters or leaves a body of the material, the material must expand or contract to its final volume or reach its final pressure and must reach its final temperature with practically no delay; some of the heat that enters can be considered to change the volume of the body at constant temperature, and

1702-403: A thermoscope and a thermometer is that the latter has a scale. A thermometer is simply a thermoscope with a scale. ... I propose to regard it as axiomatic that a “meter” must have a scale or something equivalent. ... If this is admitted, the problem of the invention of the thermometer becomes more straightforward; that of the invention of the thermoscope remains as obscure as ever. Given this,

1776-463: A universality character of thermodynamic equilibrium, that it has the universal property of producing blackbody radiation. There are various kinds of empirical thermometer based on material properties. Many empirical thermometers rely on the constitutive relation between pressure, volume and temperature of their thermometric material. For example, mercury expands when heated. If it is used for its relation between pressure and volume and temperature,

1850-466: Is a fundamental character of temperature and thermometers. As it is customarily stated in textbooks, taken alone, the so-called " zeroth law of thermodynamics " fails to deliver this information, but the statement of the zeroth law of thermodynamics by James Serrin in 1977, though rather mathematically abstract, is more informative for thermometry: "Zeroth Law – There exists a topological line M {\displaystyle M} which serves as

1924-501: Is another means of conveyance of information to and from the calculator. The on-board BASIC variants in TI graphing calculators and the languages available on the HP-48 series can be used for rapid prototyping by developers, professors, and students, often when a computer is not close at hand. Most graphing calculators have on-board spreadsheets which usually integrate with Microsoft Excel on

1998-404: Is called the latent heat of expansion at constant temperature ; and the rest of it can be considered to change the temperature of the body at constant volume, and is called the specific heat at constant volume . Some materials do not have this property, and take some time to distribute the heat between temperature and volume change. (2) Its heating and cooling must be reversible. That is to say,

2072-404: Is created, sucking liquid up into the tube. Any changes in the position of the liquid will now indicate whether the air in the sphere is getting hotter or colder. Translations of Philo's experiment from the original ancient Greek were utilized by Robert Fludd sometime around 1617 and used as the basis for his air thermometer. In his book, Pneumatics , Hero of Alexandria (10–70 AD) provides

2146-546: Is given credit for introducing two concepts important to the development of a scale of temperature and the eventual invention of the thermometer. First, he had the idea that hotness or coldness may be measured by "degrees of hot and cold." He also conceived of a fixed reference temperature, a mixture of equal amounts of ice and boiling water, with four degrees of heat above this point and four degrees of cold below. 16th century physician Johann Hasler developed body temperature scales based on Galen's theory of degrees to help him mix

2220-463: Is powered by the same processor that powered its cousin, the TI-85 , a 6  MHz Zilog Z80 microprocessor . This was an improvement over the TI-81 's 2 MHz Z80 processor. In addition, the available RAM was increased more than tenfold – from 2400 bytes to 28734 bytes (slightly more than the TI-85 ). Some of the more notable improvements of the TI-82 over the TI-81 include the following:

2294-471: Is smaller than a micrometre , and new methods and materials have to be used. Nanothermometry is used in such cases. Nanothermometers are classified as luminescent thermometers (if they use light to measure temperature) and non-luminescent thermometers (systems where thermometric properties are not directly related to luminescence). Thermometers used specifically for low temperatures. Various thermometric techniques have been used throughout history such as

TI-82 - Misplaced Pages Continue

2368-635: Is virtually identical to the TI-83. Graphing calculator A graphing calculator (also graphics calculator or graphic display calculator ) is a handheld computer that is capable of plotting graphs , solving simultaneous equations , and performing other tasks with variables . Most popular graphing calculators are programmable calculators , allowing the user to create customized programs, typically for scientific, engineering or education applications. They have large screens that display several lines of text and calculations. An early graphing calculator

2442-529: The TI-89 , TI-92 , TI-92 Plus and Voyage 200 machines show the possibility of installing some variants of other systems such as a chopped-down variant of CP/M-68K , an operating system which has been used for portable devices in the past. Tools which allow for programming the calculators in C/C++ and possibly Fortran and assembly language are used on the computer side, such as HPGCC , TIGCC and others. Flash memory

2516-419: The asc of many Basic variants, to return the code of a character, i.e. the position of the character in the collating sequence of the machine. A cable and/or IrDA transceiver connecting the calculator to a computer make the process easier and expands other possibilities such as on-board spreadsheet, database, graphics, and word processing programs. The second option is being able to code the programs on board

2590-526: The AAA batteries are being changed). The TI-82 was redesigned twice, first in 1999 and again in 2001. The 1999 redesign introduced a design very similar to the TI-73 , TI-83 Plus , and the TI-89 . It introduced a more contoured body and eliminated the sloped screen that has been common on TI graphing calculators since the TI-81. The 2001 redesign (nicknamed the TI-82 "Parcus") introduced a slightly different shape to

2664-462: The Renaissance period. In the 3rd century BC, Philo of Byzantium documented his experiment with a tube submerged in a container of liquid on one end and connected to an air-tight, hollow sphere on the other. When air in the sphere is heated with a candle or by exposing it to the sun, expanding air exits the sphere and generates bubbles in the vessel. As air in the sphere cools, a partial vacuum

2738-402: The absolute temperature of a body inside the cavity. A thermometer is called primary or secondary based on how the raw physical quantity it measures is mapped to a temperature. As summarized by Kauppinen et al., "For primary thermometers the measured property of matter is known so well that temperature can be calculated without any unknown quantities. Examples of these are thermometers based on

2812-430: The addition of a link port to enable programs and other data to be transferred between two calculators or between a calculator and a computer; the addition of two new graphing types – polar and sequence, the addition of a new type of data – the list, the expansion of the size limit of matrices to 50×50, and the (unintentional) addition of the ability to program the calculator in assembly language . The last of these provided

2886-429: The appropriate amount of medicine for patients. In the late 16th and early 17th centuries, several European scientists, notably Galileo Galilei and Italian physiologist Santorio Santorio developed devices with an air-filled glass bulb, connected to a tube, partially filled with water. As the air in the bulb warms or cools, the height of the column of water in the tube falls or rises, allowing an observer to compare

2960-776: The assembly language programming of their machines because they must be programmed in this way by putting together the program on the PC and then forcing it into the calculator by various improvised methods. Other on-board programming languages include purpose-made languages, variants of Eiffel , Forth , and Lisp , and Command Script facilities which are similar in function to batch/shell programming and other glue languages on computers but generally not as full featured. Ports of other languages like BBC BASIC and development of on-board interpreters for Fortran , REXX , AWK , Perl , Unix shells (e.g., bash , zsh ), other shells ( DOS / Windows 9x , OS/2 , and Windows NT family shells as well as

3034-599: The calculator itself. This option is facilitated by the inclusion of full-screen text editors and other programming tools in the default feature set of the calculator or as optional items. Some calculators have QWERTY keyboards and others can be attached to an external keyboard which can be close to the size of a regular 102-key computer keyboard. Programming is a major use for the software and cables used to connect calculators to computers. The most common programming languages used for calculators are similar to keystroke-macro languages and variants of BASIC . The latter can have

TI-82 - Misplaced Pages Continue

3108-597: The calculator, eliminated the glossy screen border, and reduced cost by streamlining the printed circuit board to four units. An enhanced version of the TI-82, the TI-82 STATS, was first released in 2004 in Europe. There are several improvements, most notably the statistical features as the name would suggest. In addition, it featured numerical differentiation and integration, together with complex numbers, financial functions and other improvements. In specification terms, it

3182-423: The computer side. At this time, spreadsheets with macro and other automation facilities on the calculator side are not on the market. In some cases, the list, matrix, and data grid facilities can be combined with the native programming language of the calculator to have the effect of a macro and scripting enabled spreadsheet. Thermometer While an individual thermometer is able to measure degrees of hotness,

3256-402: The current height of the water to previous heights to detect relative changes of the heat in the bulb and its immediate environment. Such devices, with no scale for assigning a numerical value to the height of the liquid, are referred to as a thermoscope because they provide an observable indication of sensible heat (the modern concept of temperature was yet to arise). The difference between

3330-541: The defining points in the International Temperature Scale of 1990 , though in practice the melting point of water is more commonly used than its triple point, the latter being more difficult to manage and thus restricted to critical standard measurement. Nowadays manufacturers will often use a thermostat bath or solid block where the temperature is held constant relative to a calibrated thermometer. Other thermometers to be calibrated are put into

3404-446: The equation of state of a gas, on the velocity of sound in a gas, on the thermal noise voltage or current of an electrical resistor, and on the angular anisotropy of gamma ray emission of certain radioactive nuclei in a magnetic field ." In contrast, "Secondary thermometers are most widely used because of their convenience. Also, they are often much more sensitive than primary ones. For secondary thermometers knowledge of

3478-527: The expansion of a liquid and independent of air pressure. Many other scientists experimented with various liquids and designs of thermometer. However, each inventor and each thermometer was unique — there was no standard scale . Early attempts at standardization added a single reference point such as the freezing point of water. The use of two references for graduating the thermometer is said to have been introduced by Joachim Dalence in 1668, although Christiaan Huygens (1629–1695) in 1665 had already suggested

3552-573: The first showing a scale and thus constituting a thermometer was by Santorio Santorio in 1625. This was a vertical tube, closed by a bulb of air at the top, with the lower end opening into a vessel of water. The water level in the tube was controlled by the expansion and contraction of the air, so it was what we would now call an air thermometer. The word thermometer (in its French form) first appeared in 1624 in La Récréation Mathématique by Jean Leurechon , who describes one with

3626-421: The following way: given any two bodies isolated in their separate respective thermodynamic equilibrium states, all thermometers agree as to which of the two has the higher temperature, or that the two have equal temperatures. For any two empirical thermometers, this does not require that the relation between their numerical scale readings be linear, but it does require that relation to be strictly monotonic . This

3700-414: The highest or lowest temperature recorded until manually re-set, e.g., by shaking down a mercury-in-glass thermometer, or until an even more extreme temperature is experienced. Electronic registering thermometers may be designed to remember the highest or lowest temperature, or to remember whatever temperature was present at a specified point in time. Thermometers increasingly use electronic means to provide

3774-401: The invention of the thermometer to any single person or date with certitude. In addition, given the many parallel developments in the thermometer's history and its many gradual improvements over time, the instrument is best viewed not as a single invention, but an evolving technology . Early pneumatic devices and ideas from antiquity provided inspiration for the thermometer's invention during

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3848-429: The keyboard. The actual programming can often be done on a computer then later uploaded to the calculators. The most common tools for this include the PC link cable and software for the given calculator, configurable text editors or hex editors, and specialized programming tools such as the below-mentioned implementation of various languages on the computer side. Earlier calculators stored programs on magnetic cards and

3922-468: The like; increased memory capacity has made storage on the calculator the most common implementation. Some of the newer machines can also use memory cards. Many graphing and scientific calculators will tokenize the program text, replacing textual programming elements with short numerical tokens. For example, take this line of TI-BASIC code: Disp [A] . In a conventional programming language, this line of code would be nine characters long (eight not including

3996-433: The material must be able to be heated and cooled indefinitely often by the same increment and decrement of heat, and still return to its original pressure, volume and temperature every time. Some plastics do not have this property; (3) Its heating and cooling must be monotonic. That is to say, throughout the range of temperatures for which it is intended to work, At temperatures around about 4 °C, water does not have

4070-478: The measured property is not sufficient to allow direct calculation of temperature. They have to be calibrated against a primary thermometer at least at one temperature or at a number of fixed temperatures. Such fixed points, for example, triple points and superconducting transitions, occur reproducibly at the same temperature." Thermometers can be calibrated either by comparing them with other calibrated thermometers or by checking them against known fixed points on

4144-441: The nearest 10 °C or more. Clinical thermometers and many electronic thermometers are usually readable to 0.1 °C. Special instruments can give readings to one thousandth of a degree. However, this precision does not mean the reading is true or accurate, it only means that very small changes can be observed. A thermometer calibrated to a known fixed point is accurate (i.e. gives a true reading) at that point. The invention of

4218-416: The possible inventors of the thermometer are usually considered to be Galileo, Santorio, Dutch inventor Cornelis Drebbel , or British mathematician Robert Fludd . Though Galileo is often said to be the inventor of the thermometer, there is no surviving document that he actually produced any such instrument. The first clear diagram of a thermoscope was published in 1617 by Giuseppe Biancani (1566 – 1624);

4292-568: The property (3), and is said to behave anomalously in this respect; thus water cannot be used as a material for this kind of thermometry for temperature ranges near 4 °C. Gases, on the other hand, all have the properties (1), (2), and (3)(a)(α) and (3)(b)(α). Consequently, they are suitable thermometric materials, and that is why they were important in the development of thermometry. According to Preston (1894/1904), Regnault found constant pressure air thermometers unsatisfactory, because they needed troublesome corrections. He therefore built

4366-463: The range 0 to 100 °C, and a larger uncertainty outside this range: ±0.05 °C up to 200 or down to −40 °C, ±0.2 °C up to 450 or down to −80 °C. Thermometers utilize a range of physical effects to measure temperature. Temperature sensors are used in a wide variety of scientific and engineering applications, especially measurement systems. Temperature systems are primarily either electrical or mechanical, occasionally inseparable from

4440-583: The readings on two thermometers cannot be compared unless they conform to an agreed scale. Today there is an absolute thermodynamic temperature scale. Internationally agreed temperature scales are designed to approximate this closely, based on fixed points and interpolating thermometers. The most recent official temperature scale is the International Temperature Scale of 1990 . It extends from 0.65  K (−272.5 °C; −458.5 °F) to approximately 1,358 K (1,085 °C; 1,985 °F). Sparse and conflicting historical records make it difficult to pinpoint

4514-428: The related 4DOS , 4NT and 4OS2 as well as DCL ), COBOL , C , Python , Tcl , Pascal , Delphi , ALGOL , and other languages are at various levels of development. Some calculators, especially those with other PDA-like functions have actual operating systems including the TI proprietary OS for its more recent machines, DOS , Windows CE , and rarely Windows NT 4.0 Embedded et seq, and Linux . Experiments with

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4588-464: The same bath or block and allowed to come to equilibrium, then the scale marked, or any deviation from the instrument scale recorded. For many modern devices calibration will be stating some value to be used in processing an electronic signal to convert it to a temperature. The precision or resolution of a thermometer is simply to what fraction of a degree it is possible to make a reading. For high temperature work it may only be possible to measure to

4662-411: The same reading)? Reproducible temperature measurement means that comparisons are valid in scientific experiments and industrial processes are consistent. Thus if the same type of thermometer is calibrated in the same way its readings will be valid even if it is slightly inaccurate compared to the absolute scale. An example of a reference thermometer used to check others to industrial standards would be

4736-405: The state of a suitably selected particular material and its temperature. Only some materials are suitable for this purpose, and they may be considered as "thermometric materials". Radiometric thermometry, in contrast, can be only slightly dependent on the constitutive relations of materials. In a sense then, radiometric thermometry might be thought of as "universal". This is because it rests mainly on

4810-568: The system which they control (as in the case of a mercury-in-glass thermometer). Thermometers are used in roadways in cold weather climates to help determine if icing conditions exist. Indoors, thermistors are used in climate control systems such as air conditioners , freezers, heaters , refrigerators , and water heaters . Galileo thermometers are used to measure indoor air temperature, due to their limited measurement range. Such liquid crystal thermometers (which use thermochromic liquid crystals) are also used in mood rings and used to measure

4884-400: The technology to measure temperature led to the creation of scales of temperature . In between fixed calibration points, interpolation is used, usually linear. This may give significant differences between different types of thermometer at points far away from the fixed points. For example, the expansion of mercury in a glass thermometer is slightly different from the change in resistance of

4958-428: The temperature of a bath of thermal radiation is proportional , by a universal constant, to the frequency of the maximum of its frequency spectrum ; this frequency is always positive, but can have values that tend to zero . Another way of identifying hotter as opposed to colder conditions is supplied by Planck's principle , that when a process of isochoric adiabatic work is the sole means of change of internal energy of

5032-408: The temperature of water in fish tanks. Fiber Bragg grating temperature sensors are used in nuclear power facilities to monitor reactor core temperatures and avoid the possibility of nuclear meltdowns . Nanothermometry is an emergent research field dealing with the knowledge of temperature in the sub-micrometric scale. Conventional thermometers cannot measure the temperature of an object which

5106-407: The temperature scale. The best known of these fixed points are the melting and boiling points of pure water. (Note that the boiling point of water varies with pressure, so this must be controlled.) The traditional way of putting a scale on a liquid-in-glass or liquid-in-metal thermometer was in three stages: Other fixed points used in the past are the body temperature (of a healthy adult male) which

5180-492: The use of graduations based on the melting and boiling points of water as standards and, in 1694, Carlo Renaldini (1615–1698) proposed using them as fixed points along a universal scale. In 1701, Isaac Newton (1642–1726/27) proposed a scale of 12 degrees between the melting point of ice and body temperature . In 1714, scientist and inventor Daniel Gabriel Fahrenheit invented a reliable thermometer, using mercury instead of alcohol and water mixtures . In 1724, he proposed

5254-485: Was Herman Boerhaave (1668–1738). In 1866, Sir Thomas Clifford Allbutt (1836–1925) invented a clinical thermometer that produced a body temperature reading in five minutes as opposed to twenty. In 1999, Dr. Francesco Pompei of the Exergen Corporation introduced the world's first temporal artery thermometer, a non-invasive temperature sensor which scans the forehead in about two seconds and provides

5328-714: Was designed in 1921 by electrical engineer Edith Clarke . The calculator was used to solve problems with electrical power line transmission. Casio produced the first commercially available graphing calculator in 1985. Sharp produced its first graphing calculator in 1986, with Hewlett Packard following in 1988, and Texas Instruments in 1990. Some graphing calculators have a computer algebra system (CAS), which means that they are capable of producing symbolic results. These calculators can manipulate algebraic expressions, performing operations such as factor, expand, and simplify. In addition, they can give answers in exact form without numerical approximations. Calculators that have

5402-531: Was originally used by Fahrenheit as his upper fixed point (96 °F (35.6 °C) to be a number divisible by 12) and the lowest temperature given by a mixture of salt and ice, which was originally the definition of 0 °F (−17.8 °C). (This is an example of a frigorific mixture .) As body temperature varies, the Fahrenheit scale was later changed to use an upper fixed point of boiling water at 212 °F (100 °C). These have now been replaced by

5476-420: Was removed from the hot liquid, then the temperature indicated on the thermometer would immediately begin changing to reflect the temperature of its new conditions (in this case, the air temperature). Registering thermometers are designed to hold the temperature indefinitely, so that the thermometer can be removed and read at a later time or in a more convenient place. Mechanical registering thermometers hold either

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