The determination of intermolecular forces in gases from their viscosity

1937 ◽  
Vol 33 (3) ◽  
pp. 363-370 ◽  
Author(s):  
D. Burnett
Keyword(s):  
Potential Energy ◽  
Intermolecular Forces ◽  
Absolute Temperature ◽  
Repulsive Force ◽  
Positive Zero ◽  
Intermolecular Force ◽  
The Absolute ◽  
Image Position ◽  
Coefficient Of Viscosity

A method of determining the coefficient of viscosity of a gas of spherically symmetrical molecules under ordinary conditions has been given by Chapman. His result is equivalent towhere m is the mass of a molecule of the gas, T is the absolute temperature, k is Boltzmann's constant 1·372. 10−16 and ε is a small quantity which later investigations on a gas in which the intermolecular force is inversely proportional to the nth power of the distance have shown to vary from zero when n = 5 to 0·016 when n = ∞ (equivalent to molecules which are elastic spheres); it may reasonably be supposed that ε is positive and less than 0·016 in all cases which are likely to be of interest, and it will be neglected in this paper. Alsoπ(r) being the mutual potential energy of two molecules (that is, the repulsive force between them is − ∂π/∂r), and r0 the positive zero of the expression in the denominator, or the largest such positive zero if there are several.

scholarly journals Absolute Calibration of Stellar Temperatures

1973 ◽  
Vol 54 ◽  
pp. 153-155
Author(s):  
H. Kienle ◽  
D. Labs
Keyword(s):  
Spectral Energy Distribution ◽  
Black Body ◽  
Absolute Temperature ◽  
Spectral Energy ◽  
Absolute Calibration ◽  
Standard Star ◽  
The Absolute ◽  
Stellar Temperatures ◽  
Image Position ◽  
Radiation Laboratory

The scale of effective temperatures Teff is based on observed absolute radiation temperatures Tr, which are defined by Planck's radiation law where TAu designs the absolute temperature of the gold point. A relative scale of radiation temperatures can be derived from spectrophotometric comparisons with a standard star. The absolute calibration of the standard star (α Lyr or Sun) demands a careful comparison with a standard radiation source of well known spectral energy distribution (Black Body or Synchrotron). With ground-based observations atmospheric extinction is to be taken into account; with extraterrestrial observations detectors may be used which are absolutely calibrated in a radiation laboratory under space conditions.

scholarly journals A determination of the radiation constant

1913 ◽  
Vol 88 (600) ◽  
pp. 49-60 ◽  
Keyword(s):  
Absolute Temperature ◽  
Absolute Zero ◽  
Fourth Power ◽  
Net Radiation ◽  
A Value ◽  
The Absolute ◽  
Boltzmann Law

According to the Stefan-Boltzmann law, the radiation emitted by a full radiator is surroundings at a temperature of absolute zero is proportional to the fourth power of the absolute temperature of the radiator, or R = σθ 4 , where R = radiation in ergs per cm 2 . per sec., θ = absolute temperature of radiator, σ = radiation constant. If the radiator is in surroundings at absolute temperature θ 1 , which are themselves full radiators, then R´ = R θ -R θ 1 = σ( θ 4 - θ 1 4 ), where R´ is the net radiation. The first important determination of the radiation constant is due to Kurlbaum, who obtained a value 5·33 × 10 -5 erg/sec. cm. 2 deg. 4 , recently corrected to 5·45 × 10 -5 erg/sec. cm. 2 deg. 4 Later investigations give results varying considerably from Kurlbaum's and from one another, and, on the whole, they indicate that Kurlbaum's value is too low. Some determinations are given in the following table:—

Rotational Specific Heat and Rotational Entropy of Simple Gases at Moderate Temperatures

1930 ◽  
Vol 26 (3) ◽  
pp. 402-418 ◽  
Author(s):  
G. B. B. M. Sutherland
Keyword(s):  
Specific Heat ◽  
Absolute Temperature ◽  
Moment Of Inertia ◽  
Planck’S Constant ◽  
Diatomic Gas ◽  
The Absolute ◽  
The Moment ◽  
Image Position ◽  
Planck's Constant

It is well known that the rotational specific heat of a diatomic gas is given bywhere R is the gas constant, σ = h2/8π2AKT, h is Planck's constant, T is the absolute temperature, K is Boltzmann's constant, and A is the moment of inertia of the molecule.

scholarly journals A new method of determining the radiation constant

1912 ◽  
Vol 86 (585) ◽  
pp. 180-196 ◽  
Keyword(s):  
Black Body ◽  
Absolute Temperature ◽  
Absolute Zero ◽  
New Method ◽  
Platinum Black ◽  
Main Current ◽  
First Case ◽  
Black Surface ◽  
The Absolute

According to stefan's law the rate of radiation of energy from a full radiator in surroundings at a temperature of absolute zero is σ θ 4 ergs per cm. 2 per sec., where θ is the absolute temperature of the radiator. If the radiator be in surroundings which are themselves full radiators, but at absolute temperature θ 1 , the rate of loss of energy by radiation is taken to be σ( θ 4 - θ 1 4 ). The classical determination of the constant σ is due to Kurlbaum, who used a surface bolometer with a platinum-black surface. The rise of temperature of the bolometer when exposed to the radiation from an approximately full radiator or "black body" was observed. The radiation was then cut off, and an equal rise of temperature was produced by increasing the main current in the bolometer. It was assumed that the energy received per second from the radiator in the first case was equal to the energy received per second from the increase of current in the second ease. The resulting value of σ was 5·33 x 10 -5 ergs per cm. 2 per sec. per deg. 4 , or 5·33 x 10 -12 watts per cm. 2 per deg. 4 .

Special relativity and thermodynamics

1969 ◽  
Vol 66 (2) ◽  
pp. 423-432 ◽  
Author(s):  
A. Georgiou
Keyword(s):  
Special Relativity ◽  
Absolute Temperature ◽  
The Absolute ◽  
Image Position

AbstractIt is shown that a revision is needed of certain transformation equations of the Planck–Einstein formulae. In particular it will be shown that the formulaemust be replaced bywhere T and Q are respectively the absolute temperature and heat of the system. Furthermore, it will be shown that both formulae for the energyare correct, but they refer to different cases.

scholarly journals XIX. The coefficient of viscosity of air

1886 ◽  
Vol 177 ◽  
pp. 767-799 ◽  
Keyword(s):  
Internal Friction ◽  
Tangential Force ◽  
Absolute Temperature ◽  
Spare Time ◽  
The Coefficient Of Friction ◽  
The Many ◽  
Coefficient Of Viscosity ◽  
Lower Plane ◽  
Different Parts

Origin and Purpose of the Investigation . Three years ago I entered on a series of researches relating to the internal friction of metals, little calculating, when I did so, that the task which I had set myself would occupy almost the whole of my spare time from that date to this. So, however, it has been, and one of the many causes of delay has been the necessity of making a re-determination of the coefficient of viscosity of air; for the resistance of the air played far too important a part in my investigations to permit of its being either neglected or even roughly estimated. The coefficient of viscosity of air may, according to Maxwell, be best defined by considering a stratum of air between two parallel horizontal planes of indefinite extent, at a distance r from one another. Suppose the upper plane to be set in motion in a horizontal direction with a velocity of v centimetres per second, and to continue in motion till the air in the different parts of the stratum has taken up its final velocity, then the velocity of the air will increase uniformly as we pass from the lower plane to the upper. If the air in contact with the planes has the same velocity as the planes themselves, then the velocity will increase v/r centimetres per second for every centimetre we ascend. The friction between any two contiguous strata of air will then be equal to that between either surface and the air in contact with it. Suppose that this friction is equal to a tangential force f on every square centimetre, then f = μ v/r , where μ , is the coefficient of friction. If L, M, T represent the units of length, mass, and time, the dimensions of μ are L -1 MT -1 . Several investigators have attempted to determine the coefficient of viscosity of air, and the following table shows how very widely the results obtained differ among each other :— Further, Maxwell finds the coefficient of viscosity of air to be independent of the pressure and to vary directly as the absolute temperature. The above author gives the following formula for finding fit the coefficient of viscosity, at any temperature θ ° C.:— μ = .0001878(1 + .00365 θ ).

scholarly journals III. On stresses in rarefied gases arising from inequalities of temperature

1878 ◽  
Vol 27 (185-189) ◽  
pp. 304-308 ◽  
Keyword(s):  
Dynamical Theory ◽  
Absolute Temperature ◽  
Principal Axes ◽  
The Absolute ◽  
The Difference ◽  
Lower Temperature ◽  
Coefficient Of Viscosity ◽  
Solid Bodies ◽  
The Given ◽  
Maximum Minimum

1. In this paper I have followed the method given in my paper “On the Dynamical Theory of Gases” (Phil. Trans., 1867, p. 49). I have shown that when inequalities of temperature exist in a gas, the pressure it a given point is not the same in all directions, and that the difference between the maximum and the minimum pressure at a point may be of considerable magnitude when the density of the gas is small enough, and when the inequalities of temperature are produced by small; solid bodies at a higher or lower temperature than the vessel containing the gas. 2. The nature of this stress may be thus defined: let the distance from the given point, measured in a given direction, be denoted by h , and the absolute temperature by θ ; then the space-variation of the temperature for a point moving along this line will be denoted by dθ / dh , and the space-variation of this quantity along the same line by d 2 θ / dh 2 . There is in general a particular direction of the line h , for which d 2 θ / dh 2 is a maximum, another for which it is a minimum, and a third for which it is a maximum-minimum. These three directions are at right angles to each other, and are the axes of principal stress at the given point; and the part of the stress arising from inequalities of temperature is in each of these principal axes a pressure equal to— 3 μ 2 / ρθ d 2 θ / dh 2 , where μ is the coefficient of viscosity, ρ the density, and θ the absolute temperature.

Residual Gas Reactions in the Electron Microscope: I. Qualitative Observations on the Water Gas Reaction

1968 ◽  
Vol 26 ◽  
pp. 292-293
Author(s):  
Richard E. Hartman ◽  
Roberta S. Hartman ◽  
Peter L. Ramos
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Gas Phase ◽  
Absolute Temperature ◽  
Residual Gas ◽  
Gas Reactions ◽  
Image Position ◽  
The Right ◽  
Water Gas ◽  
Thinning Rate

The action of water and the electron beam on organic specimens in the electron microscope results in the removal of oxidizable material (primarily hydrogen and carbon) by reactions similar to the water gas reaction .which has the form:The energy required to force the reaction to the right is supplied by the interaction of the electron beam with the specimen.The mass of water striking the specimen is given by:where u = gH2O/cm2 sec, PH2O = partial pressure of water in Torr, & T = absolute temperature of the gas phase. If it is assumed that mass is removed from the specimen by a reaction approximated by (1) and that the specimen is uniformly thinned by the reaction, then the thinning rate in A/ min iswhere x = thickness of the specimen in A, t = time in minutes, & E = efficiency (the fraction of the water striking the specimen which reacts with it).

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