# Tag Info

## New answers tagged temperature

1

If you place water (or other material) in a pressure-tight container, the water will change as heat and pressure cause its molecules to become more or less energetic and the bonds among its molecules to become more or less stable, or begin breaking apart. These changes are summarized in a chart called a phase diagram. Here is a simple phase diagram for ...

0

Thermal energy is exactly the average (with respect to the time interval of your measure) of the overall translational kinetic energy of all the particles of your system. This, in turn, can be related to the temperature of your system in case the Hamiltonian is separable into the coordinates of each one of your particles (the equipartition theorem). In ...

-1

Ah, but who says that negative absolute temperatures exist at all? This is not without its controversies. There's a nature paper here which challenges the very existence of negative absolute temperatures, arguing that negative temperatures come about due to a poor method of defining the entropy, which in turn is used to calculate the temperature. Other ...

4

In a given orbital, electron motion has nothing to do with temperature. Atoms do have a variety of electronic states and, at higher temperatures, the higher energy states are more likely to be populated. Temperature, however, is most commonly determined by the translational motion of the nucleus of the atoms. Let $v$ be the speed of a nucleus of an atom ...

3

The calibration of the digital devices drifts. When calibrating some temperature probes for a neutrino experiment we used a deionized-water ice bath. The four laboratory digital thermometers we found (all claiming between $\pm 0.05$--$0.25\,^\circ \mathrm{C}$ accuracy) read between $-0.5$ and $+1.8\,^\circ\mathrm{C}$. Clearly some were well outside their ...

0

lets be simple latent heat refers to the heat required to overcome molecular bonds. latent heat of vapourisation of water at 1 bar ,100c is 2257kJ/kg which means, that much heat is required to break inter-molecular forces and turn into gasoeus phase as pressure on molecules increases they require more heat to overcome the pressure force acting or to escape ...

0

By heating the liquid the heat energy absorbed by the molecules and then it tends to vibrate more compared to its ground state. Due to the heavier vibrations the atoms moves more far apart from its equilibrium position. Now the phenomenon called "phase change" occures. Then the liquid is transformed into gaseous state.

1

The bond that holds water as a liquid is a simple static electricity bond. it has a strength and will 'break' with sufficient energy. this happens all the time. water evaporates, when a random chance of circumstances through thermal agitation and exterior pressure are at the right amount the molecule leaves the liquid and goes flying off as a gas. the higher ...

4

Kelvin is the SI unit. It is far more common than Rankine. I cannot recall ever encountering Rankine temperature units, except in historical or humorously-backward contexts. Note that these measure temperature, not heat. The SI and "imperial" measures of heat is are the joule and the BTU, respectively. To avoid causing headaches, use SI for everything — ...

1

I think you might have actually touched on something interesting here. One explanation for the difference in temperature is simply that part of the energy removed from the balloon + air system comes from the air, so the balloon will cool more slowly when filled with air. But there might be more to the story. I haven't done any calculations on this, so it's ...

2

If you graph the temperature of your copper strip as a function of time you're going to get something like: This is because you have two effects. The light from the Sun heats the copper strip, but at the same time the strip cools. The equilibrium temperature (the dashed line) is the temperature at which the cooling balances the heating. If the intensity ...

1

So far, you have three answers to the "how is the heat transferred" part of your question, but nobody's answered the other part: How does a thermometer measure the [temperature] of atmospheric air? The answer is that both the glass and the liquid inside the glass expand when they are warmed and contract when they are chilled, but they expand/contract ...

2

Let me quote this line which says that: I touch it that it's temperature did not drop down Its better to use thermometer to check the readings as it gives you accurate reading. Please check this link as it shows what you did wrong: Why does cold metal seem colder than cold air? The process of touching and determining its temperature is wrong. There ...

-1

Can electrons reflect light? Yes. Like CuriosuOne said, electrons are shiny. I kid ye not, google on electrons shiny. Metals are shiny because they have free electrons. Check out this question about the colour of metals, where Ali said a metal is are silvery because it "reflects all wavelengths specularly (more or less)". Also see this article by William ...

1

I tested it against a control and it worked. Used longneck glass bottles. Didn't measure the difference but the difference was notable to the touch after half an hour.

0

To make an object "invisible", one important thing you have to do is to stop it from blocking the light behind it from the observer's perspective. If you have an opaque object that emits/reflects no visible light, then what you will see is a black silhouette of the object. The only way it will be invisible then is if it's against a completely black ...

0

To summarize: hotter => bluer, but more radiant => brighter. Something which is very hot, but invisible, would need to be small and have an energy output proportionate to the lower surface area. An energy source of a given number of watts is indeed easier to "hide" if it emits mainly at higher frequencies. This is what makes cobalt-60 dangerous when ...

0

1) It's true that the peak wavelength for a black body decreases with temperature. But let's say you want to know what temperature has what peak wavelength. Well, you can Google on "peak wavelength temperature calculator" and try for yourself. But I'll give you the short form. Since visible light is in the range of 400 to 700 nm, your body would have to be ...

13

Planck's Law gives us the intensity of black body radiation as a function of temperature: $$B(\lambda,T)=\frac{2hc^2}{\lambda^5}\cdot \frac{1}{e^{\frac{h c}{\lambda k_B T}}-1}$$ If we plot a normalized plot of this curve for different temperatures, you see the following: As you can see, it does look like the higher temperatures make the relative ...

37

You're right that as the temperature increases, shorter wavelengths receive a higher proportion of thermally radiated power, and longer wavelengths a smaller proportion, because of the shifting Boltzmann distribution of your molecules' kinetic energy, and therefore the shifting power spectrum of the light they emit. However, most of the objects you see ...

1

I am not particularly familiar with the primon gas you are linking to, but similar ideas have been tossed around for a long time; see, for example this page for many references (including the topic you mention). The first two topics (quantum mechanics and statistical mechanics) are particularly relevant to your question; I'll concentrate on the second one, ...

6

In some sense yes. The temperature is defined as an imaginary time in Matsubara Green's functions or some path integrals. Thus, a negative inverse imaginary temperature can be considered as a time. Here is a quotation from Alexander Altland, Ben Simons "Condensed Matter Field Theory": "Thus, real time dynamics and quantum statistical mechanics can be ...

0

From a really awesome book called "100 tips to crack the IIT" by Vivek Pandey and Paras Arora Temperature, in some ways, shows the willingness of an object to give up its heat energy to other objects. It is like talkativeness in a way. Some people cannot hold in the secrets they know. So, they keep talking to other people all the time. How much someone ...

2

Yes! You have to think about the amount of energy that is hold in the coffee. The amount is (almost) exactly the same the moment before you add the milk than just in the moment after adding it. So if you consider the energy of a cup at room temperature as zero energy, the amount of energy stays the same as the milk adds no energy. But(!) the temperature ...

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