how can a thermistor,along with appropriate electrical circuitry,be used to measure temperature?
813595
a thermistor is a resistor whose resistance changes with temperature. Because of the known dependence of resistance on temperature, the resistor can be used as a temperature sensor.\n\nSo, add a thermistor into a simple circuit with a power supply and a meter to measure current and you have the essence of a device to measure temperature.\n\nGet a bucket, fill it with ice and leave it till the ice has half melted. The temperatue of the water will be 0 degrees C. Pop in the thermistor (suitably electrically insulated) and measure the current.\n\nBoil a pan of water on the stove. As it's bubbling the water will be exactly 100 Degrees C, and again measure the current.\n\nUsing both values you can calibrate your new electronic thermometer!
1183365
A thermocouple can be a temperature sensor or it can be a means of converting heat energy to electricity. Many deep space probes use thermocouples (a series of thermocouples) powered by radioisotope decay for electricity production.
136243
measuring device of some sort (scale, ruler, thermometer)
354014
what sort of sensors are u interested in. if it is light then it can be measured using photoconductive or ptotovoltaic devices.
904529
Think of different ways you could measure it and describe those methods.  Check the reference section of a library for the CRC Handbook for the specific heat of known reference materials.  Does the specific heat change with temperature?  How could you test that?  Think about measurement methods you could do, without fancy or expensive equipment.  Think about how you could test how good your equipment is and how you can get the best accuracy from it.  If you actually do it, you can make a good science project of it.
593035
In electronics, thermocouples are a widely used type of temperature sensor and can also be used as a means to convert thermal potential difference into electric potential difference. They are cheap, interchangeable, have standard connectors, and can measure a wide range of temperatures. The main limitation is accuracy; system errors of less than 1 °C can be difficult to achieve.\n\nA thermopile is a group of thermocouples connected in series.\n\nPrinciple of operation\nIn 1821, an Estonian physicist named Thomas Johann Seebeck discovered that when any conductor (such as a metal) is subjected to a thermal gradient, it will generate a voltage. Any attempt to measure this voltage necessarily involves connecting another conductor to the "hot" end. This additional conductor will then also experience the temperature gradient, and develop a voltage of its own which will oppose the original. Fortunately, the magnitude of the effect depends on the metal in use. Using a dissimilar metal to complete the circuit will have a different voltage generated, leaving a small difference voltage available for us to measure, which increases with temperature. This difference can typically be between 1 to about 70 microvolts per degree Celsius for the modern range of available metal combinations. Certain combinations have become popular as industry standards, driven by cost, availability, convenience, melting point and chemical properties, stability, and output.\n\nIt is important to note that thermocouples measure the temperature difference between two points, not absolute temperature.\n\n\n\nIn most applications, one of the junctions — the "cold junction" — is maintained at a known (reference) temperature, while the other end is attached to a probe. For example, in the image below, the cold junction will be at copper tracks on the circuit board. Another temperature sensor will measure the temperature at this point, so that the temperature at the probe tip can be calculated.\n\nHaving available a known temperature cold junction, while useful for laboratory calibrations, is simply not convenient for most directly connected indicating and control instruments. They incorporate into their circuits an artificial cold junction using the "other" thermally sensitive device (such as a thermister or diode) to measure the temperature of the input connections at the instrument, with special care being taken to minimize any temperature gradient between terminals. Hence, the voltage from a known cold junction can be simulated, and the appropriate correction applied. This is known as cold junction compensation.\n\nUsually the thermocouple is attached to the indicating device by a special wire known as the "compensating" or "extension" cable. The terms are specific. "Extension cable" uses wires of nominally the same conductors as used at the thermocouple itself. These cables are less costly than thermocouple wire, although not cheap, and are usually produced in a convenient form for carrying over long distances - typically as flexible insulated wiring or multicore cables. They are recommended for best accuracy.\n\n"Compensating cables" on the other hand, are less precise, but cheaper. They use quite different, relatively low cost alloy conductor materials whose net thermoelectric coefficients are similar to those of the thermocouple in question, but which do not match them quite as faithfully as extension cables. The combination develops similar outputs to those of the themocouple, but the operating temperature range is restricted to keep the mis-match errors acceptably small.\n\nThe extension cable or compensating cable must be selected to match the thermocouple. It generates a voltage proportional to the difference between the hot junction and cold junction, and is connected in the correct polarity so that the additional voltage is added to the thermocouple voltage, compensating for the te
928307
Any temperature-sensing device whose resistance is a function of temperature is inherently nonohmic; i.e., does not display a constant resistance with varied current flow or varied applied voltage. This is due to the fact that current flow will cause the device to heat and do its job which is to change resistance. An NTC device could conceivably "run away" with a constant applied voltage; as current increases it heats up and its resistance goes down resulting in further current increase. Conversely, a PTC device could conceivably run away with a constant applied current; as it heats up its resistance increases resulting in a higher voltage drop across it, which produces more heating, etc. For this reason, when using a thermistor it is a good idea to measure its resistance with a very sensitive (low sensing voltage and current) ohmmeter to minimize spurious heat input.
824652
Generally speaking, an increase in temperature leads to an increase in electrical conductivity. \n\nMany multimeters today include a feature that can allow us to use them as digital thermometers, by plugging in the appropriate probe. \n\nIf you have such a digital multimeter (try Radio Shack for an inexpensive one) they may sell probes ready made, or you can try to make your own using a typical diode (1N4004 silicon,  or 1N34 germanium, or similar) as a probe. \n\nThe forward voltage drop across a silicon diode is about 0.6 volts, across a gemainium diode is about 0.34 volts. Calibrate your probe by dunking it into an ice bath (zero centigrade) and then into boiling water (200 centigrade). Record the voltage drop across the diode at those temperatures. Make sure it is properly encapsulated (use silicone rubber, if you are making your own) and let it return to ambient temperature before making subesquent measurements.\n\nWith a little effort, you should be able to develop a chart with which to convert the voltage reading to a temperature measurement. (Use graph paper.) If you have the right kind of diode, it should be fairly linear. If you are in doubt, try some measurements at temperatures in between the extremes and compare to a known good thermometer.\n\n20 NOV 06, 0320 hrs, GMT.
1101939
A thermocuple might be the one you seek. \n\nThe seebeck effect on thermocouple uses this theory, as there are two different material soldered together to make a single V or U shaped bar, there is a point where those two metals met. When we heat that point, the heat will move the electron, and since one metal has different coefficient than the other, so the electron will move from one metal to the other, thus an electric current will be created.\n\nPeltier effect, uses the vice versa theory, thus if we put electrical current through that thermocouple, then the thermocouple will need to absorb heat from it surroundings, thus, it will lower the ambient temperature.\n\nI haven't got any clue on how effective does this "refrigerant" work, but I think It might, might, might, work..
823030
You could use a resistor in series for the voltmeter and a shunt resistor in parallel with the ammeter.  You can also use a signal amplifier to transform the input signal to one that is within the range of the meter.  If it is a panel type meter, do not forget to change the scale behind the meter.\n\nJeffM
458975
Try Thermo.com/neslab contact them with any questions you have.
375391
You can get a USB temperature logger here:\nhttp://www.measurementcomputing.com/cbicatalog/USB-501.asp?dept_id=480&pf_id=1758&mscssid=S4E7V96D5UD48MSURGA3T5M8NH9H9EP0\nIt's not a regular medical thermometer, but it's the closest thing I could find.  This is best if you want to take repeated measurements over a long period of time.\n\nIf you want only a few measurements per day, the easiest thing is take your temperature with a regular thermometer and type it in.\n\nIf you enter the date/time along with your temperature in Excel, you can make a nice chart of your body temperature.
263946
Have each page work on the same princable as the bi-metallic thermometer.  Try to find two materials the expand differently than eachother because of heat, or you could use humidity to expand one material more than the other. You could probably find some material that contracts (or expands) when an electrical current passes through it. place a strip of this along the top and bottom of each page. Thats all i can think of right now.\nCool question by the way.
115436
With a Magnetometer. See below for more detail.
210078
1-thermostat: It senses water temperature and deflects if the water is hot enough, causing a way open for water to circulate around engine cool the engine down.\n\n2- A sensor for battery resource which say to generator when to charge the battery.\n\n3- A sensor for oil level, you should get out of car \nand bring it out from oil tank and watch it, (oil gauge)\n\n4- Oil pressure sensor: alarms if oil pressure is dropped.\n\n5- Back gear light: turns the back gear lamp on if sense the gear is for back.\n\n6- Door opening: alarms if a door is open.\n\n7- Air bag: a mechanical sensor for impact.\n\n8- Gas tank: senses the amount of gas in the tank and say\n it.\n\n9- speed: a digital or mechanical sensor which can say the\n Amount of speed.\n\n10- Rpm: a digital or mechanical sensor which can say how fast is engine turning.
977894
Electronic sensors can be extremely temperature-dependant.\n\nThe reason is that electronics are semiconductors, and these devices work on the principal of electrons migrating from one area to another in the chip.  The warmer the chip, the easier it is for these electrons to move across the "junction boundaries."  At any given temperature, it takes a certain voltage for the electrons to migrate.  Increase the temperature, and more electrons move across the bopundaries for the same voltage, or conversely a lower voltage moves the same number of electrons across a warmer boundary.  Since all electronic sensors use these voltage and current values to represent whatever it is that they are sensing, changes in the performance of the sensor electronics appear as offsets or other errors in the readings.\n\nIn order to avoid these wrong readings, the temperature-sensitive electronic parts of the instrument are encased in what are often called "ovens" where they are heated to a controlled temperature, and the performance of all the electronics is factory calibrated at this temperature.  When the instrument is field-calibrated just prior to use, it performs a couple of readings of known values and compares these to the values received during factory calibration.  The differences in the factory calibration and field calibration results are then used to adjust the instrument's answers to account for long-term drift which occurs as a result of the aging of various critical components.\n\nWhen you use the instrument in the real world, it must be allowed to "stabilize" (come up to a stable temperature) so that the field self-calibration and calibration-verification proceses will function properly and return the real values for long-term-drift compensation.  If this is not allowed to happen, the values which the instrument THINKS are long-term drift will actually be due to temperature variances, and these flawed long-term-drift corrections will cause innacurate readings.  And since they will be constantly changing until the temperature becomes stable, the errors will change from one reading to another.  You can see this for yourself by performing a calibration and then reading a known "blank" sample immediately after the equipment is turned on, and then again 15 minutes later.  There will be some significant differences between the two readings of the same sample performed by the same instrument.\n\n- - - - - - - -  \n\nThere is also a mechanical stabilization needed for many instruments, particualrly those that rely on an optical path.  This is to pevent flexing of the instument's measurement systems which can cause varying alignment and thus introduce errors.  That is why when a complex and sensitive instrument such as a spectrophotmeter or gas chromatograph is first installed, it must be on a solid concrete slab and is allowed to equalize to the lab's temperature and humidity for a couple of days before the mountings or base are re-adjusted and a site calibration performed to ensure all is set up correctly.  You would be amazed by the errors that can be introduced by having one leg of the base raised or lowered by the thickness of a sheet of paper.
678334
This is a bit complicated but you might try this....\n\nStart with a centralized heat source, preferably electrical, so it should remain fairly constant.  You will need three thermometers, each to be held in place by their own stands.  Place a block or bar of metal so that it does not quite touch the heat source, and in contact with its thermometer at the far end.  Place a wooden bowl with water (a metal or glass container would taint your study ) near the heat source with its thermometer just in the water.  Place your last thermometer the same distance from the heat source, thus testing the heat conductivity of air.  If you had access to more thermometers and stands, you could place them at various points in a line from the heat source.  You will notice that the last thermometer will by far have the lowest readings.