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:—

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 .

Gas Laws

2009 ◽  
Author(s):  
Christopher O. Oriakhi
Keyword(s):  
Absolute Temperature ◽  
Absolute Zero ◽  
Standard Temperature ◽  
Gas Laws ◽  
Temperature Scales ◽  
Straight Line ◽  
Temperature And Pressure ◽  
The Absolute ◽  
The Relationship ◽  
Boyle’S Law

Volumes and densities of gases vary significantly with changes in pressure and temperature. This means that measurements of the volumes of gases will likely vary from one laboratory to another. To correct for this, scientists have adopted a set of standard conditions of temperature and pressure (STP) as a reference point in reporting all measurements involving gases. They are 0°C (or 273 K) and 760mmHg or 1 atm (or 1.013×105 N m−2 in S.I. units). Therefore standard temperature and pressure, as used in calculations involving gases, are defined as 0°C (or 273 K) and 1 atmosphere (or 760 torr). (Note: For calculations involving the gas laws, temperature must be in K.) Boyle’s law states that the volume of a given mass of gas at constant temperature is inversely proportional to the pressure. The law can be expressed in mathematical terms: V α 1/P or PV = k at constant n and T Since P×V = constant, problems dealing with P–V relationships can be solved by using the simplified equation: P1V1 = P2V2 Here P1, V1 represent one set of conditions and P2, V2 represent another set of conditions for a given mass of gas. Charles’s law states that the volume of a given mass of gas is directly proportional to its absolute temperature. So if the absolute temperature is doubled, say from 300 K to 600 K, the volume of the gas will also double. A plot of the volume of a gas versus its temperature (K) gives a straight line. A notable feature of such a plot is that the volume of all gases extrapolates to zero at the same temperature, −273.2◦C. This point is defined as 0 K, and is called absolute zero. Thus, the relationship between the Kelvin and Celsius temperature scales is given as: K = 0°C + 273. Scientists believe that the absolute zero temperature, 0 K, cannot be attained, although some laboratories have reported producing 0.0001 K.

scholarly journals Albedo and size of (99942) Apophis from polarimetric observations†

2006 ◽  
Vol 2 (S236) ◽  
pp. 451-454 ◽  
Author(s):  
Alberto Cellino ◽  
Marco Delbò ◽  
Edward F. Tedesco
Keyword(s):  
Accurate Determination ◽  
Absolute Magnitude ◽  
Phase Curve ◽  
Efficient Tool ◽  
A Value ◽  
Size Estimate ◽  
The Absolute ◽  
Polarization Phase

AbstractWe have obtained the first accurate determination of the albedo of (99942) Apophis, by means of polarimetric observations carried out at the VLT. The observations allowed us to obtain the slope of the polarization–phase curve of this object, from which an albedo estimate of 0.33 ± 0.04 could be obtained. From our observations we also obtained a new estimate of the absolute magnitude: H = 19.7 ± 0.2 (assuming G=0.25, which applies to S- and Q-type asteroids). Based on these results, we derive for the size of Apophis a value of 270 ± 30 meters. The accuracy of this size estimate is mostly related to uncertainties in H, whereas the obtained albedo value should be considered more robust. Our observations convincingly show that polarimetry is an effective and efficient tool to obtain accurate albedos and sizes for small and faint potentially hazardous asteroids.

scholarly journals IV. A determination of the electromotive force of the weston normal cell in semi-absolute volts

1914 ◽  
Vol 214 (509-522) ◽  
pp. 147-198 ◽  
Keyword(s):  
Electromotive Force ◽  
Order Of Accuracy ◽  
Absolute Determination ◽  
A Value ◽  
Great Progress ◽  
The Mean ◽  
The Absolute ◽  
The Times ◽  
Made In

The measurement of the E. M. F. of the Weston cell affords the best means of comparing the performances of different methods and instruments for the absolute determination of the ampere. Great progress has been made in the last six years, but the most recent determinations by independent methods, giving equal promise of accuracy, still show discrepancies covering a range of 2 parts in 10,000, which must be debited for the most part to the difficulty of the absolute determination of current. Each method in itself appears to give an order of accuracy of repetition approaching, or even exceeding, 1 in 100,000. It is therefore of special interest and importance to compare the results of methods differing as widely as possible in experimental details in endeavouring to arrive at a value comparatively free from the constant errors which may beset any particular type of method. The measurements described by Mr. Shaw in the following paper were made by the method of the Weber bifilar electrodynamometer, as modified by Clerk Maxwell and Latimer Clark, which has not hitherto been employed for work of the highest accuracy, and which merits attention on account of its many fundamental points of difference from recent methods. The instrument originally supplied to McGill College for this purpose was a faithful copy of Clerk Maxwell’s instrument at Cambridge, of which the theory is given together with a figure and description in his ‘ Electricity and Magnetism,’ vol, 2, p. 367. The chief sources of error in this instru­ment were (1) the uncertainty of insulation of the coils, which proved to be of the order of nearly one half of 1 per cent.; (2) the difficulty of determining the mean radii of the coils, which were wound with silk-covered wire; (3) the want of rigidity of the pulley arrangement for equalising the tensions of the suspending wires, and the imperfect elasticity of the control, which depended too much on torsion, and made it impossible to obtain readings consistent to 1 in 1000 for the deflections or the times of oscillation. These defects were so fatal to accurate work even of the order of 1 in 10,000, which was all that it was originally contemplated, that it was found necessary to reconstruct the instrument entirely until nothing remained of the original except the frame, and even that required stiffening to a material extent.

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.

A radiometric determination of the Stefan-Boltzmann constant and thermodynamic temperatures between -40 °C and +100 °C

1985 ◽  
Vol 316 (1536) ◽  
pp. 85-189 ◽  
Keyword(s):  
Thermodynamic Temperature ◽  
Black Body ◽  
Fourth Power ◽  
Platinum Resistance ◽  
Boltzmann Constant ◽  
A Value ◽  
Standard Deviations ◽  
Radiometric Determination ◽  
Gas Thermometry

The total radiant exitance of a black body at the temperature of the triple point of water, T tp (273.16 K), and at a series of other temperatures in the range from about 233 K ( — 40 °C) to 373 K (100 °C), has been measured by using a cryogenic radiometer. From the measurements at T tp a value for the Stefan—Boltzmann constant or has been calculated: ( r = (5.66967 + 0.00076) x 10 -8 W m -2 K -4 . This is the first radiometric determination of or having an uncertainty comparable with that calculated directly from fundamental physical constants. This measured value differs from the calculated one by 13 parts in 10 5 , which is less than the combined standard deviations of the measured and calculated values. mbined standard deviations of the measured and calculated values. From the measurements of exitance at the other temperatures, values of the corresponding thermodynamic temperature T have been calculated by using Stefan’s fourth-power law. Since the temperature of the radiating black body was also measured by platinum resistance thermometers calibrated on IPTS-68, values of ( T — T 68 ) were obtained. These range from about — (5 + 1.6) mK at 20 °C to — (28 ±2.5) mK at 100 °C and + (5 + 1.5) mK at —40 °C. The results confirm to within a few millikelvins the departure of T 68 from T above 0 °C already discovered by gas thermometry and show that similar departures, but of opposite sign, exist down to the lowest temperature measured, — 40 °C. The uncertainties associated with these new values of T and ( T — T 68 ) are similar to those of the best gas thermometry.

scholarly journals Mpemba Effect- the Effect of Time

2021 ◽  
Author(s):  
Jianan Wang
Keyword(s):  
Gravitational Field ◽  
Black Body ◽  
Black Body Radiation ◽  
Absolute Temperature ◽  
Time Effect ◽  
Gravitational Redshift ◽  
Fourth Power ◽  
Heat Flows ◽  
Nature Of Time ◽  
The Absolute

By analyzing the relation between time and speed, the relation between time and gravitational field, the gravitational redshift of photon and the black-body radiation theorem, the conclusion that time on an object is proportional to the fourth power of the absolute temperature of the object is obtained. Applying the above conclusion about the nature of time, the author analyzes the Mpemba effect and the inverse Mpemba effect, and reaches the following conclusion: the Mpemba effect is the time effect produced when heat flows from objects into space, and the "inverse" Mpemba effect is the time effect produced when heat flows from space into objects.

Cosmological Entropy and Seeking of Genesis of Time

2015 ◽  
Vol 7 (1) ◽  
pp. 1336-1345
Author(s):  
Rakesh Teja Konduru
Keyword(s):  
Space Time ◽  
Absolute Temperature ◽  
Absolute Zero ◽  
Zero Temperature ◽  
Space Curvature ◽  
Different Temperatures ◽  
Acceleration And Deceleration ◽  
Negative Space ◽  
The Absolute

Influenced with symmetry of entropy and time in nature, we tried to invoke relation between entropy and time in space-time with new dimension. And also provided how Hubble’s constant related with entropy of universe. Discussed about how entropy of universe behaves at different temperatures and at different time values of universe. We showed that age of universe is equivalent to Hubble’s constant. And showed how naturally entropy arrives from the manipulations in gravity from Einstein’s equation “00”. And from these results we concluded that universe is isotropic, homogeneous with negative space curvature i.e. K= -1 but not flat K=0 (which doesn’t explain acceleration and deceleration of universe). From these results of gravity, entropy, temperature and time we discussed the genesis of time. And proposed that at absolute zero temperature universe survives as a superconductor and that particular temperature is called as “Critical Absolute Temperature (TAB). And genesis of time occurs at first fluxon repulsion in the absolute zero temperature of universe. 

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