What is Thermometer: Definition and 84 Discussions

A thermometer is a device that measures temperature or a temperature gradient (the degree of hotness or coldness of an object). A thermometer has two important elements: (1) a temperature sensor (e.g. the bulb of a mercury-in-glass thermometer or the pyrometric sensor in an infrared thermometer) in which some change occurs with a change in temperature; and (2) some means of converting this change into a numerical value (e.g. the visible scale that is marked on a mercury-in-glass thermometer or the digital readout on an infrared model). Thermometers are widely used in technology and industry to monitor processes, in meteorology, in medicine, and in scientific research.
Some of the principles of the thermometer were known to Greek philosophers of two thousand years ago. As Henry Carrington Bolton (1900) noted, the thermometer's "development from a crude toy to an instrument of precision occupied more than a century, and its early history is encumbered with erroneous statements that have been reiterated with such dogmatism that they have received the false stamp of authority." The Italian physician Santorio Santorio (Sanctorius, 1561-1636) is commonly credited with the invention of the first thermometer, but its standardisation was completed through the 17th and 18th centuries. In the first decades of the 18th century in the Dutch Republic, Daniel Gabriel Fahrenheit made two revolutionary breakthroughs in the history of thermometry. He invented the mercury-in-glass thermometer (first widely used, accurate, practical thermometer) and Fahrenheit scale (first standardized temperature scale to be widely used).

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  1. D

    Remote button style thermometer

    I am trying to find these little remote button sized thermometers that I used at an old job. They interfaced via USB, through a little cradle that you plugged them into. They would measure temperature over a 24 hour (or so) period. You then take them from where you were taking the measurement...
  2. C

    Newton's law of cooling and thermometer

    Homework Statement Hi, I need some help in solving Newton's law of cooling problem. Use Newton’s law of cooling to determine the reading on a thermometer 5 min after it is taken from an oven at 72 ◦ C to the outdoors where the temperature is 20 ◦ C, if the reading dropped to 48 ◦ C after...
  3. E

    Which Temperature Sensing Technique Offers the Highest Sensitivity?

    Hi Wich temperature sensing technique is the most sensitive one?
  4. D

    Developing equation for rare gas thermometer using F

    Homework Statement Develop an analogous equation for a rare gas thermometer using the Fahrenheit scale as reference points. Homework Equations T = aL + b where L is length of metal rod used to determine scale, a and b are constants expansion coefficient = 2.7315 The...
  5. N

    Temperature of thermometer and temperature of material constituents

    Hello-- Suppose that I insert a thin-needle thermometer into a porous material (such as snow) that consists of air, ice, and water. The thermometer is used to measure a temperature. Is it reasonable to assume that the temperature measured by the thermometer is the same as the temperatures...
  6. S

    Which Type of Sensor is More Accurate: Thermocouple or RTD?

    I wonder whether the accuracy of that thermometer with a type K sensor is as follow: encironment: 90'C Sensor type: resistance sensor so the accuracy = +/- 90*0.005+0.5 = +/-0.95'C Thanks for your help.
  7. fluidistic

    Lab report questions, gas thermometer

    Hi PF! I have a lab report to do about a gas thermometer experience that I couldn't do. I'm very saddened about this because I should have manipulate mercury but the earlier group broke a container of mercury and so the class had to be disinfected and closed for some days. Basically it...
  8. N

    Incorrect Thermometer Readings: What's the Boiling Point?

    1. A thermometer is calibrated wrongly. At the melting point, it reads -10 degree celsius. At 50 degree celsius, it reads 60 degree celsius. What does the thermometer read at the boiling point? 2. I think this is logic-based. 3. I drew a table but got confused.
  9. C

    A Thermometer That Could Measure Negative Temperature

    Just for fun, I was thinking of trying to design one. How could we design a thermometer that could accurately measure negative temperature of a spin system?
  10. C

    Designing a Thermometer to Measure Negative Temperature

    My homework problem says to construct a thermometer which could accurately measure a negative temperature. I have no idea how to do this. Any help would be very appreciated!
  11. O

    Understanding the Function of a Constant Volume Thermometer

    Does anybody know how a Constant volume thermometer works? I know that one of the reference points is the triple point of water, but I'm not sure how different gases are used along with this reference point to get different values of temperature for certain known processes. for instance...
  12. K

    How Does Temperature Affect the Movement of Mercury in a Thermometer?

    Homework Statement (a) The tube of a mercury thermometer (made of Pyrex glass) has an inside diameter of 0.140 mm. The bulb has a volume of 0.275 cm3. How far will the thread of mercury move when the temperature changes from 10.5 degrees Celsius to 33.0 degrees Celsius? (b) Determine a...
  13. M

    Mathematical Model of Thermometer

    Homework Statement Find height of Hg column in a thermometer as a function of temperature and time Homework Equations Supposed to derive my own in this case...using the engineering methodology with conservation and accounting equations. Total Energy in + Total Energy Out + Work done on the...
  14. A

    Temperature change of water at triple point in a constant-volume gas thermometer

    Homework Statement P(at triple point in torr of water) 100 200 300 400 P(in torr for gas w/ respect to Pressure above) 127.9 256.5 385.8 516.0 The previous table gives the observed values of the pressure of a gas in a constant-volume gas thermometer at an unknown temperature T and at the...
  15. D

    Building a Bimetallic Thermometer: Aluminium and Brass Sheets

    I am currently working on a bimetallic thermometer using alumium and brass. The coefficient of linear and volumetric thermal expansion of aluminium is 23 and 69 respectively. The coefficient of linear and volumetric thermal expansion of brass is 19 and 57 respectively. I am using...
  16. S

    Copper resistance thermometer - temperature

    Homework Statement a piece of copper wire (rho_20 = 1.7*10^-8 ohm-m) is being used as a resistance thermometer.At 20 degrees celsius, the wire is known to have a resistance of 170 ohms. when the wire is immersed in a hot oil bath, its resistance increases to 173.4 ohms. if the temperature...
  17. A

    Calibration of a thermometer naphthalene

    I would like to know why are naphthalene, acetanilide, benzoic acid, and adipic acid used in calibration of thermometers. Do those compounds have any specific property that makes them adecute for this process?
  18. A

    How do you construct an OVEN THERMOMETER?

    I need to construct an oven thermometer out of scratch using any materials that are purchasable. Our restrictions are: - No mercury - The product must be able to read from 250 degrees fahrenheit to 500. - MUST FIT IN THE OVEN PLZ. thank you
  19. B

    Thermometer pressure physics problem

    Homework Statement A constant volume gas thermometer has a pressure of 5830 Pa at 47 °C. What would the pressure be for -99 °C (in Pa)? Homework Equations Pf = Pi * (Tf/Ti) The Attempt at a Solution Ti = 47 deg C = 320 deg K Tf = -99 deg C = 174 deg K Pi = 5830 pa = 0.05755...
  20. P

    How Is the True Temperature Calculated from a Miscalibrated Thermometer?

    a thermometer reads -.3 degrees celsius at ice point and 100.6 degrees celsius at steam point. find the true temperature of a thermometer if thermometer read 18.2 degree celsius The Attempt at a Solution this is actually a simple math question that i need a little help with. i know what...
  21. M

    Range of a thermometer - and bulb size

    I have a question. How does the size of the bulb (mercury) affect the range of the thermometer? I know that to increase the range, the bore size of the capillary tube should be large. Would the size of the bulb affect the range? If bulb is large - then there will be more mercury - so...
  22. W

    Thermometer Height Conversion at Different Temperatures?

    Homework Statement Constant volume of a thermometer is given(v), given the hieght of a column of mercurey at T_{o} supports, what is he hieght at T_{2}? Homework Equations The Attempt at a Solution I really don't know, can someone start me off please.
  23. F

    Mercury in glass-laboratory thermometer doesn't stick to glass?

    Why the mercury in glass-laboratory thermometer doesn't stick to glass?
  24. T

    What is a vapor bulb thermometer ?

    What is a "vapor bulb thermometer"? The problem statement vapor bulb thermometer I'm simply looking for a definition. I haven't been able to find it on the internet. Before looking in a library, I was wondering if anyone knows which book to look for, or where on the internet a definition...
  25. P

    Can boiling water effectively sterilize a clinical thermometer?

    Homework Statement A clinical thermometer cannot be sterilised by placing it in boiling water. Why not?Homework Equations none.The Attempt at a Solution I assume the liquid is mercury. In the book they said a clinical thermometer has a kink at the end (so when it is out of the mouth it dosen't...
  26. S

    Thermal Expansion of thermometer in ice water

    Here is a two part problem I'm having trouble with: The length of the column of mercury in a thermometer is 4cm when the thermometer is immersed in ice water and 23.5cm when the thermometer is immersed in boiled water. a) What should be the length at room temperature 22degreesCelcius? I...
  27. M

    Misc. How to build your own cheap thermometer

    Help Quick! ok so i made a cheap thermometer this the manual to make the thermometer 1. Tap water 2. Rubbing alcohol (do not drink this) 3. Clear, narrow-necked plastic bottle (11-ounce water bottles work well) 4. Food coloring 5. Clear plastic drinking straw 6. Modeling...
  28. F

    How Does Temperature Scale Impact Gas Pressure Calculations in Thermometers?

    The gas in a constant-volume gas thermometer has a pressure of 87.0kPa at 104*C. (a)what is the pressure of the gas at 50.0*C? for this i used the eqn of (87/104)(104-50) like it said in the book and still didnt get the answer right.
  29. M

    Knowing how to use a thermometer

    i got a question when is knowing how to use a thermometer VERY IMPORTANT for us?
  30. M

    Thermometer Help: Avoiding Wrong Measurement

    ok well my science teacher told us to make a thermometer, i have everything needed for it but i just got one question, all the bottles that we drink on have you know the little mountains those little balls at the bottom, and if it has that then the measurement will be wrong, what can i put...
  31. K

    Universal Mountain/Sea Thermometer

    Taking the definition we have in Europe (I don't know the US version of it) of temperature (we use Celsius Degree here most of the time) : 0° is defined as the triple point of water, and 100° the boiling point. Then I suppose it is usual to make a linear approx (dilatation is linear in first...
  32. P

    Thermometer measures the amount of infra-red radiation only

    A thermometer measures the amount of infrared radiation only, right? so, if equivalent amount of visible light is illustrated on the bulb, the temperature for the infrared rises much more, doesn't it?
  33. R

    Using a Thermistor as a Crude Thermometer

    Speaking to my physics teacher the other day, he said that you can use a thermistor as a crude thermometer...He didn't really explain it very well and I just got completely confused. Can anyone explain it to me? Thanks!
  34. R

    Mercury thermometer temperature problem

    The length of the mercury coloumn in a mercury thermometer is 5cm when the bulb is immersed in water at the triple point (273.16k). What is the temperature if it reads 6.0cm? What will the length of coloum be if immersed in boiling water (at steam point)? I'm new to this forum, but would...
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