# What is Temperature dependence: Definition and 30 Discussions

Viscosity depends strongly on temperature. In liquids it usually decreases with increasing temperature, whereas, in most gases, viscosity increases with increasing temperature. This article discusses several models of this dependence, ranging from rigorous first-principles calculations for monatomic gases, to empirical correlations for liquids.
Understanding the temperature dependence of viscosity is important in many applications, for instance engineering lubricants that perform well under varying temperature conditions (such as in a car engine), since the performance of a lubricant depends in part on its viscosity. Engineering problems of this type fall under the purview of tribology.
Here dynamic viscosity is denoted by

μ

{\displaystyle \mu }
and kinematic viscosity by

ν

{\displaystyle \nu }
. The formulas given are valid only for an absolute temperature scale; therefore, unless stated otherwise temperatures are in kelvins.

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1. ### A Experiments for temperature dependence of persistent supercurrent?

Imagine, in a mercury ring (superconductivity below Tc=4.15 K) we establish a persistent supercurrent. Then we organize temperature cycles (T-cycles) in the cryostat, from 3 K to 2.5 K and back. According to the BCS theory of superconductivity, the pair density decreases at warming, i.e. a not...
2. ### Calculate Conductivity Temperature Dependence in Semiconductors

I have to plot the conductivity dependence of temperature and I have problems with obtaining the right dependency of \mu and n. But let's focus only on carrier concentration first. For n I used the third equation. From what I understand N_D is a constant. I want my plot to look like this: But...
3. 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...
4. ### Refraction problem (temperature dependence)

Hi Everybody I am doing an experiment for a school project where I have chosen to see is the index of refraction changes in a body of water when the temperture changes. So I am using the angle of incidence and refraction to measure using snells law. The Problem: Obviously I need a container to...
5. ### Speed of sound in steel dependance on temperature

Hello, Nice easy question for you all today: I would like to know how the speed of sound in steel varies with temperature. A google search didnt reveal a great deal, so if a physicist could confirm the relationship, that would be much appreciated. I know that: v = √shear modulus/density...
6. ### Temperature dependence of Cv at very large volume

Homework Statement In the case of a gas obeying the equation of state \begin{align}\frac{Pv}{RT}&=1+\frac{B}{v}\end{align} where ##B## is a function of ##T## only, show that, \begin{align}c_v&=-\frac{RT}{v}\frac{d^2}{dT^2} (BT)+\left(c_v\right)_0\end{align} where ##\left(c_v\right)_0##...
7. ### A Carrier concentration temperature dependence; semiconductors

Hi all, I'm reviewing device physics and I would like to understand how majority and minority carrier concentrations for both N- and P-type substrates change with temperature. My reference, Pierret's Semiconductor Device Fundamentals, has this figure: and I want to generate curves for all...
8. ### I Small temperature dependence in diamagnetic material

Hi everybody! I´m chemist doing new materials and my understanding of physics is quite basic. I have a sample (single phase) of Ba and Ge and it shows diamagnetism in the magnetic susceptibility measurement, however it show a small temperature dependent behavior. As far as I understand...
9. ### Temperature dependence of the index of refraction of air

The index of refraction for a gas depends on temperature, as well as pressure. What is an experiment that would determine the temperature dependence of the index of refraction of air?
10. ### Temperature Dependence of Donor Ionization Energies

Donor ionization energies are calculated via the hydrogen-like model and use the static dielectric constant and effective mass to modify the screening between the electron and the donor. Nice and simple, I get it. But in a material the ionized electron needs to go someplace - presumably the...
11. ### Temperature dependence of relaxation time T1 vs T2

Hi, when we assume a obejct with increasing dynamics with increasing temperature, the longitudinal relaxation time T1 should decrease. Since we have, let's say at a frequency 100 MHz , more fluctuations of B0. Ok, then the transversal relaxation time T2 must increase with increasing...
12. ### Hydrogen/Helium Emission Spectra Temperature Dependence

Hi all, Does anyone know where I can find data details of how Emission Spectra depends on temperature for the following materials: Single Hydrogen Molecular Hydrogen (H2) Helium That is, as I heat up each of the above materials by themselves, from room temperature to thousands of degrees, I'd...
13. ### 303 Stainless Steel Properties at High Temps

Does anyone have a source for 303 stainless steel mechanical properties (YS, UTS, modulus, poisson's) with variation to temperature, especially around 800C? I've been searching a lot of sites... Or would it be fine to assume 303 has "good resistance to scaling at up to 871C" from...
14. ### Why Does the 31P NMR Spectrum of PF5 Depend on Temperature?

Why is the 31P NMR spectrum of PF5 temperature-dependent? PF5 has two different F environments (3 F, 2 F) and 19F has spin 1/2 so we'll be getting a quartet and a triplet with some overlap I guess. (Also not sure about peak intensities or if we can even predict them) So what changes, and how...
15. ### Temperature dependence of the light yield in scintillators

Hi, I have a question regarding the temperature dependence of the light yield in scintillators. I will attach a figure from the book by Glenn F. Knoll, So the question is, what is causing the reduction in light yield with high temperatures, when the decay time for the scintillation...
16. ### Why is DeltaGo Temperature Dependent in Standard State?

I see why, numerically speaking, deltaGo, defined as deltaGo = - RT ln K or deltaGo = deltaHo - TdeltaSo would be temperature dependent. But why is deltaGo temperature dependent, when it is simply Gibbs Free Energy at Standard State? Is this essentially saying that the definition of standard...
17. ### Temperature dependence of Lennard-Jones potential

My question is not so much about the Lennard-Jones potential, although I mentioned it in the title, but of the "force field" thinking in general. So a lot of people are (were) interested in the phase transition temperature of the Ising model. How realistic is the model in the sense that it...
18. ### Temperature dependence of the electrical resistivity of a metal

the electrical resistivity ρ of a metal is proportional to the probability that an electron is seattered by the vibrating atoms in the lattice an this probability is in turn proportional to the mean square amplitude of vibration of these atoms.How dose the electrical resistivity ρ of the metal...
19. ### Energy Gap of Intrinsic Semiconductors: Temperature Dependence

Energy gap dependence on temperature for intristic semiconductors (Si,Ge) I need help on this topic, where to find text about this, and models that describe it (Varshni's model, linear model,...)
20. ### Exploring the Temperature Dependence of Semiconductor Energy Gaps

THE TEMPERATURE DEPENDENCE OF THE ENERGY GAPS IN SEMICONDUCTORS Where I can find text about this topic and models that describe this? I know about Linear and Varshni models, and what about two (or more) other models?
21. ### Possible error in temperature dependence of Gibbs energy in textbook?

Homework Statement In the attached picture, I am wondering if there is an error in equation (6.34). In equation (6.33), the partial differential of G/T is taken with respect to T. In (6.34), however, the partial differential of G/T is taken with respect to 1/T and the same outcome is...
22. ### Temperature dependence of Resistance

Homework Statement A wire has a resistance of 2 ohm at 25 C and 2.5 ohm at 100 C . Find the temperature coefficient of resistance of the wire. The Attempt at a Solution This question is a very easy one, but I had a doubt - R=Ro(1 + αθ) Here θ is the change in temperature. I proceed...
23. ### The temperature dependence of target ionization(Z(T))

i am studying on heavy ion fusion, i need to know about the temperature dependece of target ionization,Z(T)is obtained sloving the equation of state (EOS)based on the Thomas -fermi model. Also,More(1981) is derived an equation to Z(T),but this relation is not correct to low temperature. i...
24. ### Temperature dependence of contact angle in liquids

How does contact angle change with temperature and why? Does capillary rise have a temperature dependence?
25. ### Temperature dependence on intrinsic carrier concentration

How does one calculate the intrinsic carrier concentration Ni for silicon as a function of temperature? I know the equation ni^2 = Nc*Nv exp(-Eg/kT) can be used, but then another equation is needed to find the energy band gap Eg. The effective density of states values Nc and Nv are well...
26. ### How Does Temperature Affect the Resistance of a Nichrome Heating Element?

Homework Statement A toaster with a Nichrome heating element has a resistance of 150 omega at 20degrees Celsius and an initial current of 2 A. When the heating element reaches its final temperature, the current is 1.73 A. What is the final temperature of the heating element? Homework...
27. ### Temperature Dependence of Dielectric Constants

Does anyone have information on temperature dependence of dielectric constants? I haven't been able to find anything general enough on Google. I'm particularly interested in Polyethylene, Teflon, and Air but a general description would also be appreciated.
28. ### Temperature dependence of LED emission bandwidth

Homework Statement If an LED is used in an optical communications system, explain what would happen to the temporal spread caused by material dispersion in the fibre as the LED is cooledHomework Equations (having trouble using the latex equation editor, sorry) I know that the temporal...
29. ### Temperature dependence of a latent heat.

Homework Statement You Need to find the enthalpy of sublimation of solid A at 300K. The following equilibrium vapor pressure measurements have been made of pure A : (1) At 250K, the pressure is 0.258 bar and (2) At 350K, the pressure is 2.00 bar. The following heat capacity data is known...
30. ### Temperature Dependence on Pressure Change in Gases

I have a simple question. If we increase the pressure of a gas by decreasing its volume without heat exchange, does the temperature always change? Or does it depend how fast we change the pressure? I tried to find the answer for this question, unfortunately I couldn’t. Thanks for any help!