Temperature Definition and 1000 Threads

Temperature is a physical quantity that expresses hot and cold. It is the manifestation of thermal energy, present in all matter, which is the source of the occurrence of heat, a flow of energy, when a body is in contact with another that is colder or hotter.
Temperature is measured with a thermometer. Thermometers are calibrated in various temperature scales that historically have used various reference points and thermometric substances for definition. The most common scales are the Celsius scale (formerly called centigrade, denoted as °C), the Fahrenheit scale (denoted as °F), and the Kelvin scale (denoted as K), the last of which is predominantly used for scientific purposes by conventions of the International System of Units (SI).
The lowest theoretical temperature is absolute zero, at which no more thermal energy can be extracted from a body. Experimentally, it can only be approached very closely (100 pK), but not reached, which is recognized in the third law of thermodynamics.
Temperature is important in all fields of natural science, including physics, chemistry, Earth science, astronomy, medicine, biology, ecology, material science, metallurgy, mechanical engineering and geography as well as most aspects of daily life.

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  1. M

    High temperature (~950 C) heating blanket

    Hi, I need to heat up a flat surface in a controlled way from room temperature to approximately 950 C. The surface will be some square meters large. Is there any way doing this without combustion, that is using a electric heating blanket? Does anyone know if such blankets exist? (Have already...
  2. T

    What is the Correct Way to Plot a 2D Ising Model Temperature Chart?

    Hi, I've been given a homework to do based on 2D Ising model. Ive already read plenty of articles bout 2d ising model but I'm not fairly certain about some things. I got to do a chart similar to the one I attached. Correct me if I am wrong, but on the Y axis, I have to put average of...
  3. K

    "Heat resistance temperature" and melting point?

    I've got a kitchen bowl made of polypropylene, it states that the "heat resistance temperature is 90 degree cel", while on Google, I found that the melting point of PP is 160 degree cel. I understand that melting point is the temperature in which the atoms/molecules change its state from solid...
  4. Diracobama2181

    Heat Capacity of a Fermi Gas at Low Temperature

    I find that $$U=\int Z \epsilon D(\epsilon) e^{-\epsilon β}d\epsilon=\frac{gV}{(2\pi)^3}\int Z \frac{(\hbar)^2k^2}{2m}k^2 (4\pi)e^{-β\frac{(\hbar)^2k^2}{2m}}dk$$ where g=2s+1=2, $$Z=e^{βµ}$$ and $$D(\epsilon)=\frac{gV}{(2\pi)^3}k^2 4\pi$$ for the density of states From here, I can use $$c_v...
  5. pangru

    Physics Career in cuprate high temperature superconductor physics

    Hello, I am interested in physics of cuprate high temperature superconductors (Cuprate_SC) However, I heard that it is "out-of-dated" topic in solid state physics and almost impossible to find group/foundation to do research in this field. I am doing PhD right now and I consider moving...
  6. T

    Repost/Merged Threads - Density: pressure and temperature dependency

    See image
  7. P

    Temperature and non-equilbrium thermodynamics

    Suppose we have a body that isn't a black body, but has an arbitrary emission spectrum. In the general case, can the radiation from this body be characterized as having a temperature, and if so, how? If not, what conditions are needed to make the concept of temperature meaningful in this case?
  8. Frigus

    Do two boxes expand equally with temperature if one has a Hole?

    Suppose we have two boxes of same material and same size but one have a hole in it and if we raise the temperature with equal amount then does two box expand equally?
  9. Frigus

    Temperature: Definition & Atomic Level Effects

    What is temperature? The simple definition I get in books is that it is the measure of coldness or hotness,but what in real it is at the atomic level what does happens to the atoms when we we work on substance by heating.
  10. C

    Temperature needed to destory bacterial spores

    What is the minimum temperature required to kill any highly resistant bacterial spore?
  11. men5j2s

    Estimate the temperature change due to vaporizing liquid

    I'm releasing pressurized propellant into another chamber which is at atmospheric pressure, I want to estimate the temperature to which that chamber will drop to and the rate at which the liquid (collecting in the new chamber) will boil. The second chamber is open to atmosphere via a small...
  12. Anand Sivaram

    Thermal Imaging of people and background temperature

    Any object with a temperature emits corresponding EM waves. Thermal imaging works by considering our temperature of 37C/98.4F/310K, and it corresponds to 9.3um LWIR as per Wien's law. I was thinking about the following summer scenarios in which how it would work. 1) If...
  13. Frigus

    Why do we need different temperature scales?

    I want to know that why we have defined value of temperature of boiling point and melting point of water different on different scales, as I can think we need to know temperature so we have given a certain value to melting point and boiling point of water and we have given them some value but...
  14. Sai Maurice

    Temperature change brought about by radiation

    I tried modeling the problem quite a few ways. one was to say that the difference between the heat emitted by the room and the heat emitted by the bulbs would equal the heat absorbed by the room, and that could allow us to calculate temperature. This did not work. I'd appreciate your help
  15. P

    Calculate internal temperature and energy changes

    Question (These are incorrect values) Attempt I used and then found the respective change in temperature. However for the last question I have no idea, do I sum up the net change in temperature and use But then what is the work and how do we figure it out?
  16. Rifat amin

    Below 20K, The specific heat capacity c of silver varies with temperature

    Not attempt
  17. E

    Temperature dependence of ΔS°, ΔG° and ΔH°

    I was taught that standard ΔS°, ΔG° and ΔH° are the corresponding quantities measured under standard conditions which I was told was 0.1M for solutions, 1 bar for gases, but importantly also at 298K. On many places on the internet, however, I have read that 298K is not actually a standard...
  18. T

    Fuel/oxidizer preheating to a high temperature

    imagine you burn something, like H2 in O2. let's say you have a nice flame with a temperature T. for the sake of this discussion let's assume that T is 1000. what happens if you preheat both H2 and O2 to 1000 first? is the resulting flame temperature higher? does the flame look the same? what...
  19. alfab

    Measuring Water Temperature & Diffusion Coefficient with Pollen

    Problem: We wish to find the temperature and the diffusion coefficient of water by measuring the velocity of pollen grains in the medium, due to brownian motion and other forces. Attempt: We have a video clip and are using the program Tracker to measure the position of the pollen grains over...
  20. S

    Pendulum Clock -- Change in frequency with change in temperature

    1) I do not quite understand how the phrase remain accurate to 1 second in 24 hours? , means ΔP = 1 second, 2) I also don't understand how pendulum period P should be 24 hours What is the reasoning for both? The solution is as such P = 2π √(L/g) P' = 2π √((L+L α δT)/g) ΔP = P'- P = 2π...
  21. A

    Calculating the temperature of a conductor from the current through it

    I'm not sure if this is the right place for this but I have a question about the relationship between current through a conductor and the heat dissipated by the material. Given the current, resistance, and specific heat of a material as well as the specific spatial dimensions is there a way to...
  22. PGaccount

    I Exploring the Origin of Unruh Temperature: Theories and Implications

    A uniformly accelerating observer registers a temperature T = 1/2π Or an observer hovering near a black hole. According to current understanding, what are the best ideas about the origin of this temperature?
  23. TachyonLord

    Resistance of Platinum decreases with an increase in temperature ?

    Basic Procedure The experiment basically involves finding the null point on the Carey Foster's bridge with the PRT as the unknown resistance and using a Resistance box as the variable resistance. In the above diagram, P and Q are 2 fixed resistors of equal resistances. For obtaining the first...
  24. gdritz

    Molten metal temperature vs Induction Coil Current

    Hi guys, I'm new here. I have been analyzing the behavior of cast iron melts in induction furnaces and realized that at the end of the melt the current increases slightly. The power remains the same. Physically, does anyone know the reason? I imagine to be related to the magnetic permeability...
  25. piyush_1903

    Exploring Frequency & Temperature: Theory & Experiment

    So, my apparatus consists of a basic wooden plank with a nail on one end and a guitar tuner on the other. I plan on using a heating lamp to control the temperature of the apparatus, which is placed inside an insulation box, and use a non-contact infrared thermometer to measure the temperature of...
  26. men5j2s

    Temperature of a compressed gas

    How can I calculate the temperature changes of a pressurized gas as it is in a cylinder, then as it is when flowing into another vessel? my best guess was using the ideal gas law (with help from this forum), but I feel like I'm using it wrong. P = 300bar or 296.08 atm V = 112 L (is this...
  27. H

    Is it possible to calculate an incandescent bulb's temperature from V?

    Hi! I have a question: Is it possible to calculate incandescent light color temperature based on it''s input voltage? For example, if for example 100w light bulb rated for 220V gives light with color temperature of 2800k then what would color temperature be at 110v? As voltage is now 2 times...
  28. granzer

    Why doesn't the stagnation temperature change in a stator?

    I am studying the rotary compressor and I have understood that the stagnation pressure and stagnation temperature both increase in the rotor stage (as energy is being added). I also read that in the stator stage the stagnation temperature remains a constant but there is loss of stagnation...
  29. fsonnichsen

    Precision Temperature Measurement

    What is the most precise way to log temperature in the laboratory? I am concerned with resolution and precision here, not accuracy. RTDs don't seem to cut it. Almost all that I have looked at and tried only have a resolution of around 0.1 deg C. I was hoping for 10X better than that- Thanks...
  30. S

    How to calculate the transition temperature in this problem?

    Summary: The transition Sn(s, gray) ⇌ Sn(s, white) is in equilibrium at 18°C and 1 atm pressure. If ΔS = 8.811K mol for the transition at 18°C and if the densities are 5.75 g/cm3 for gray tin and 7.28 g/cm3 for white tin, calculate the transition temperature under 100 atm pressure The...
  31. Baibhab Bose

    Final temperature of an adiabatic process between two reservoirs

    *Here, no mention of these reservoirs being a gas, so I'm not sure if I can use the PV=nRT or the P*V^(gamma)=K equation. SO I am left with only the 1st law. If I can write dQ1( going out from object 1)= Cp (indep of T)*(Tf-T1) dQ2(coming into the object 2)= Cp*(T2-Tf)...
  32. H

    Partial Temperature of a Gas in a Mixture

    Is there such a thing as a partial temperature of a gas in a mixture? Partial pressure is commonly accounted for and used. It seems that if there are molecules of different masses colliding in a mixture, their average respective velocities in a mixture should be different based on transfer of...
  33. L

    Conductor Temperature Rise, Three-Phase Vs. Single-Phase

    Good Morning, I am not coming up with an answer in my search, could anyone confirm or deny whether a circuit conductor would experience more temperature rise with three-phase current than if the same R.M.S. current was single-phase. Alternating Current, 60 Hertz. If you want to know why I want...
  34. A

    Describe the relationship between temperature and specific volume?

    I set up an experiment where I put a fixed quantity of water in a cylinder fitted with a movable piston. I slowly add heat to the system, as expected both the temperature and the volume will increase but the volume will not increase significantly (steep line), until some point where some gas...
  35. S

    Changing the Air Temperature with a hair dryer

    Hi, so I found this on another old "AP" High School Finals Exam. I think I may be super lost. Because the only way that I can think about is KE = 3/2kT. And then that the difference of the Kinetic Energy of the air Particles is the Q supplied by the heater inside the air dryer. So ## \frac...
  36. electr0dave

    How can I mix gases in a chamber measuring only pressure and temperature

    Hello all! Basically I intend to create an environment inside a chamber with variations of CO2 percentages, using electrovalves. The mixing gas is always compressed air + CO2. For example: create a 50% CO2 concentration with a total pressure of 2 Bar. The chamber is closed, and compressed air...
  37. fernelau

    Understanding the Impact of Convex Lens Focal Length on Water Temperature

    Summary: Hi, I'm doing an assessment for Physics on Optics topics, but I can't really explain how the CV affect the RV CV : Focal length of convex lens RV : Temperature of water after 20 minutes under the sun How I should explain for the temperature difference? 🤔 Please help, Thanks.
  38. L

    Thermodynamic Systems - Volume, Final Pressure and Final Temperature

    Mass = 0.12kg Initial temp = 500°c = 773K Initial pressure = 0.8 MPa = 800,000 Pa Final volume = 90L R = 287 Jkg^-1K^-1 1) Initial Volume V=mRT/P 0.12 x 287 x 773 / 800,000 = 26,662.12m^3 2) Final Pressure P2 = P1P2^1.2/V2^1.2 800,000 x 26,662.12^1.2 / 90 = 1,816,095,330 Pa = 1,816 MPa 3)...
  39. andrea1313

    Black cube, maximal and minimal value of equilibrium temperature T

    So i had this problem and I want a rigourous solution. The answer should be : Tmin=(I/sigma)^(1/4) and Tmax=(sqrt(3I)/sigma)^1/4
  40. S

    Misc. How Can I Best Insulate a Safe to Protect Heat-Sensitive Materials?

    Hello, I would like to ask you something about prevention from temperature equalization. I would really appreciate it if you can answer. To begin with, I want to store specific material into a breathable microfiber bag and place it inside a safe. This material is susceptible to heat and...
  41. J

    The association of degrees of freedom with temperature

    I delved a bit into the kinetic theory of gases and it got me wondered how it is discovered that the temperature, and thus heat capacity, is dependent on the number of degrees of freedom of a molecule or atom. I know that from the piston experiment a certain constant value can be found for the...
  42. J

    I How Do You Calculate Initial Pressure and Final Volume in Adiabatic Expansion?

    I have a compressed pure gas at a specific temperature and volume. (T1, V1) It suddenly (adiabatically) expands until it's at ambient pressure and a specific temperature. (P2, T2). Given: T1, V1, T2, and P2, I want to find P1 and V2. There's a great example in wikipedia which is almost...
  43. Nikhil Rajagopalan

    Relation between temperature and average translational kinetic energy.

    Dear Experts, I have read from various sources that the temperature of a gas is related to the "average translational kinetic energy" of a molecule of gas. When there are molecules that support motion other than translational ,which may also have rotational and vibrational motion, How does those...
  44. AttoBlaze

    If pressure decreases, does temperature then decrease?

    So, quick disclaimer: i am very young. only 12. i might also misspell some thing or not translate it correctly. i just like physics, so don't expect much. So, i was reading in my science textbook (as a hobby) and it asked to describe some examples, in which i should find out wether the work on...
  45. wishstar

    What is the equation to calculate the temperature

    What is the equation to calculate the temperature at a given distance from a heat source (inside a green house)? Example: I want to calculate the temperature at 2m, 3m, 5m, 7m from the heating object like a heater.
  46. Brendan Webb

    Flow Rate and Temperature Relationship in Air Change Calculations

    MODERATOR'S NOTE: NO TEMPLATE BECAUSE THREAD WAS SUBMITTED TO ONE OF THE REGULAR FORUMS Summary: Calculate the air change rate required to keep a certain temperature In question d above, you were asked to calculate how long the air flow in the system would be active in a day. Now factor in...
  47. Suppaman

    B Does my speedy spaceship (.999+C) have a temperature?

    I assume that as time is moving much slower on the ship and that may affect the frequency of heat radiation. I am not sure how to phrase the question because I do not want to assume any answers. I did ask Mr. Google but no results.
  48. Wrichik Basu

    Superconductivity at "ambient temperature"?

    On 23rd July, 2018, physicists from Indian Institute of Science (IISc) Bangalore, said that they had discovered superconductivity at room temperature. The paper in arxiv aroused doubts in the scientific world, but nothing was said after that. However, the team has reviewed the paper to a new...
  49. W

    Gas Law - increasing temperature with constant volume held

    I've set up a simple experiment to look at the ideal gas laws. My experiment is relatively simple in that I have a metal tube which is capped on one side. I am then pressurising the tube with air to 100 psi and locking it off. My thought is that as the pressure increased, with volume held...
  50. R

    B Understanding Color & Temperature

    In my quest to understanding radiation of the electromagnetic spectrum and the things around me I would like to confirm if I understand this correctly... - The color of objects around us doesn't always mean they are hotter than another just because of the color it has, for example: A blue...
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