TRANSMISSION OF LIGHT BY WATER DROPS 1 TO 5 μ IN DIAMETER

1944 ◽  
Vol 22a (3) ◽  
pp. 53-66 ◽  
Author(s):  
R. Ruedy
Keyword(s):  
Surface Tension ◽  
Water Vapour ◽  
Wave Length ◽  
Incident Beam ◽  
Index Of Refraction ◽  
Optical Methods ◽  
Propagation Of Light ◽  
Water Drops

The size of the drops formed when water vapour condenses is related to the work performed against the surface tension. For the determination of the size by optical methods, Mie's solution of the electromagnetic equations for the propagation of light of wave-length λ in a medium containing small spherical drops of radius a indicates that as the ratio α = 2πa/λ increases from 0 to 20, the intensity of the light received in the prolongation of the incident beam passes alternately through maximum and minimum values. At distances from the drops greatly exceeding λ, the first maximum lies close to α = 2π, the second is near α = 8.6, and the subsequent peaks are less distinct and tend to repeat themselves at α = (m + 3/4)π. As a result of these fluctuations the light seen through a cloud of particles with diameters greater than about 1 μ is coloured. The theory accounts for the cycles in the changes of colour observed when the diameter increases, and enables a determination of the radius of growing drops. With increasing radius, the influence of the index of refraction m decreases; for m = ∞ the positions and values of the peaks differ only slightly from those obtained with water.

UNDERCOOLING AND RATE OF CONDENSATION IN STEAM

1944 ◽  
Vol 22a (6) ◽  
pp. 77-94 ◽  
Author(s):  
R. Ruedy
Keyword(s):  
Surface Tension ◽  
Helmholtz Equation ◽  
Water Vapour ◽  
Vapour Pressure ◽  
Wave Length ◽  
Visible Radiation ◽  
Second Stage ◽  
Water Drops

The first and most difficult stage in the condensation of water vapour is the increase in the size of the drops until their radius satisfies the Kelvin–Helmholtz equation for the degree of undercooling or supersaturation reached at the temperature Tc of the vapour; the second stage is the increase in size by continued addition of molecules until the vapour pressure p(v) of the drop containing v molecules approaches the pressure p∞ exerted at the same temperature by a pool of water. A gradual enlargement to visible drops follows. Consideration of the number of collisions of the molecules with the drops forming at the vapour pressure pc of steam, and the loss of molecules by virtue of the higher vapour pressure of small drops leads to the conclusion that at condensation temperatures between 0° and 50 °C. the centres of condensation in the absence of dust or ions contain fewer than a hundred molecules. When the degree of supersaturation corresponds to larger drops, condensation is bound to fail. The conclusion drawn from the theory is confirmed by the values obtained in the tests with flowing steam and with cloud chambers. At higher temperatures larger drops act as nuclei. The growth in the second stage is also extremely rapid, at least until the radius equals in size the wave-length of visible radiation. Water drops of this size, that is, drops that produce coloured diffraction rings, behave as large drops. The heat of condensation may furnish part of the work to be performed against the surface tension.

scholarly journals On the surface-tension of liquids investigated by the method of jet vibration

1907 ◽  
Vol 80 (535) ◽  
pp. 26-27 ◽  
Keyword(s):  
Surface Tension ◽  
Cross Section ◽  
Wave Length ◽  
Standing Waves ◽  
Exact Determination ◽  
Relative Measurements

1. According to Lord Rayleigh’s theory of jet-vibrations, measurement of the length of the standing waves and the velocity and cross-section of a jet, together with the density of the liquid, affords the necessary constants for the calculation of the surface-tension. Notwithstanding the great fundamental advantages of this method, it has only been used in very few cases, and only for relative measurements of the surface-tension. The explanation hereof is to be found in the great difficulties connected with the adequate exact determination of the wave-length, and cross-section or velocity of the jet. As none of the methods in use for the measurement of these quantities could be taken as satisfactory, the main object of this investigation has been to work out really good methods for them.

scholarly journals On the ionization of light gases by X-rays. II.—The ionization of hydrogen by recoil electrons

1933 ◽  
Vol 141 (845) ◽  
pp. 686-696 ◽  
Keyword(s):  
Total Energy ◽  
Wave Length ◽  
Practical Importance ◽  
Incident Beam ◽  
Direct Methods ◽  
X Rays ◽  
Recoil Electron ◽  
X Ray ◽  
Experimental Errors

In Part I, p. 669, a technique has been described for determining the ratio of the ionization in a light gas (hydrogen or helium) to that in air when ionized by the same X-ray beam, homogeneous rays of medium wave-length and soft heterogeneous rays being available for the measurement. The ionization ratio can be converted into the ratio of the energies absorbed by the two gases by making use of the known value of the ratio of the energies required to form a pair of ions in the two gases; and since the ionization in air is due almost entirely to photoelectrons and the absorption coefficient is known, the energy in the incident beam can be obtained from the energy absorbed by air; thus the energy absorbed by the light gas can be correlated with the energy in the incident beam. The radiation of medium wave-length (about ½ A.) ionizes the light gas chiefly through the agency of recoil electrons, so that after applying a correction (obtained from the soft ray ratio) for the ionization due to photoelectrons, the fraction of the energy in the incident beam converted into recoil electron energy by the gas may be obtained, and compared with the predictions of the quantum theory of recoil scattering. In this paper the comparison is carried out with measurements on hydrogen, and for convenience it will be made between the experimental and calculated values of the ionization ratios. Excluding the early work of Shearer already mentioned in I no experimental determination of the total energy associated with recoil electrons has hitherto been made by any method as direct as the present one, though less direct methods have been employed. In general, however, the experimental technique was open to criticism, and the interpretation of the measurements uncertain, so that it is not surprising that the results were inconsistent either with one another or with theory. It is also possible to calculate the total energy associated with recoil electrons from other experimental facts concerning recoil scattering, but the experimental errors involved combine to make the final result very unreliable. The energy associated with recoil electrons is, however, not only of theoretical interest but also of great practical importance, since all effects arising from scattering, in the scattering substance itself, are due to recoil electron emission.

Laboratory Notes by Professor Tait b. Determination of the Surface-Tension of Liquids by the Ripples produced by a Tuning-Fork

1875 ◽  
Vol 8 ◽  
pp. 485-485
Keyword(s):  
Surface Tension ◽  
Tuning Fork ◽  
Wave Length ◽  
Slight Modification ◽  
Simple Waves ◽  
Image Position

A slight modification of a formula given by Sir W. Thomson (Phil. Mag. ii. 1871), shows that the period (t) of oscillation of a particle in a deep mass of liquid agitated by simple waves or ripples iswhere λ is the wave-length, T the surface-tension, and ρ the density of the liquid. By producing, with the aid of a massive tuning-fork, steady ripples in various liquids all subjected to the same conditions, and measuring micrometrically the length of these ripples, the quantity T is determined with considerable accuracy from the above formula.

Note on optical methods of measuring the size of small water drops

1936 ◽  
Vol 32 (3) ◽  
pp. 493-498 ◽  
Author(s):  
John G. wilson
Keyword(s):  
Drop Size ◽  
Rayleigh Scattering ◽  
Wave Length ◽  
Free Fall ◽  
Optical Methods ◽  
Numerical Density ◽  
Single Drop ◽  
Small Water ◽  
Water Drops ◽  
Temperature Equilibrium

The very small water drops which are considered in this note are as a rule met with in the form of clouds with a high numerical density of drops. The interior of such a cloud will never be in temperature equilibrium with the walls of a containing vessel, and under these conditions measurements of the rate of fall of the top of a cloud are not measures of the Stokes free fall of a single drop. Optical methods of measurement assume, therefore, a particular importance. The angular diameter of the diffraction halo has long been used as a measure of drop size in clouds; the applicability of this method for small drops will be considered. The criterion of “Rayleigh scattering” has also been employed as showing that the diameter of the drops in question was very much smaller than the wave length of light. A third method which may be applied to drops of diameter of the order of one wave-length will be discussed.

scholarly journals I. On the determination of the indices of refraction of various substances for the electric ray. I. Index of refraction of sulphur

1896 ◽  
Vol 59 (353-358) ◽  
pp. 160-167 ◽  
Keyword(s):  
Narrow Range ◽  
Direct Method ◽  
Coal Tar ◽  
Index Of Refraction ◽  
Optical Methods ◽  
Light Waves ◽  
Optically Transparent ◽  
A Direct Method

The indices of refraction of transparent substances have been determined by the usual optical methods. There is still a large number of substances like the various rocks, wood, brick, coal-tar, and others which are not transparent to light, so that their indices could not be obtained. These substances are, however, transparent to electric radiation; and the present investigation was undertaken to find a direct method of determining their indices with a sufficient amount of accuracy. Even in the case of optically transparent substances, the indices are only known for the narrow range of light waves.

Kinematic Approximations in TED and RHEED Analysis of Reconstructed Surfaces

1990 ◽  
Vol 48 (2) ◽  
pp. 396-397
Author(s):  
L. -M. Peng ◽  
M. J. Whelan
Keyword(s):  
Electron Diffraction ◽  
Kinematic Analysis ◽  
Incident Beam ◽  
High Energy ◽  
Energy Electron ◽  
Great Success ◽  
High Energy Electron ◽  
Kinematic Approximation ◽  
Reconstructed Surfaces

In recent years there has been a trend in the structure determination of reconstructed surfaces to use high energy electron diffraction techniques, and to employ a kinematic approximation in analyzing the intensities of surface superlattice reflections. Experimentally this is motivated by the great success of the determination of the dimer adatom stacking fault (DAS) structure of the Si(111) 7 × 7 reconstructed surface.While in the case of transmission electron diffraction (TED) the validity of the kinematic approximation has been examined by using multislice calculations for Si and certain incident beam directions, far less has been done in the reflection high energy electron diffraction (RHEED) case. In this paper we aim to provide a thorough Bloch wave analysis of the various diffraction processes involved, and to set criteria on the validity for the kinematic analysis of the intensities of the surface superlattice reflections.The validity of the kinematic analysis, being common to both the TED and RHEED case, relies primarily on two underlying observations, namely (l)the surface superlattice scattering in the selvedge is kinematically dominating, and (2)the superlattice diffracted beams are uncoupled from the fundamental diffracted beams within the bulk.

Fast calibration of CBED patterns for quantitative analysis

1993 ◽  
Vol 51 ◽  
pp. 674-675
Author(s):  
M.A. Gribelyuk ◽  
M. Rühle
Keyword(s):  
Reciprocal Lattice ◽  
Accurate Determination ◽  
Incident Beam ◽  
Crystal Thickness ◽  
Structure Model ◽  
Beam Direction ◽  
Transmitted Beam ◽  
Reciprocal Vector ◽  
On Line

A new method is suggested for the accurate determination of the incident beam direction K, crystal thickness t and the coordinates of the basic reciprocal lattice vectors V1 and V2 (Fig. 1) of the ZOLZ plans in pixels of the digitized 2-D CBED pattern. For a given structure model and some estimated values Vest and Kest of some point O in the CBED pattern a set of line scans AkBk is chosen so that all the scans are located within CBED disks.The points on line scans AkBk are conjugate to those on A0B0 since they are shifted by the reciprocal vector gk with respect to each other. As many conjugate scans are considered as CBED disks fall into the energy filtered region of the experimental pattern. Electron intensities of the transmitted beam I0 and diffracted beams Igk for all points on conjugate scans are found as a function of crystal thickness t on the basis of the full dynamical calculation.

Automation of selected brazes' dynamic properties in high-temperatures' measurement process

2013 ◽  
Vol 18 (2-3) ◽  
pp. 33-41
Author(s):  
Dominik Sankowski ◽  
Marcin Bakala ◽  
Rafał Wojciechowski
Keyword(s):  
Surface Tension ◽  
High Temperatures ◽  
Dynamic Properties ◽  
Automatic Measurement ◽  
Measurement Methodology ◽  
Joining Process ◽  
Wetting Force ◽  
Research Grant

Abstract The good quality of several manufactured components frequently depends on solidliquid interactions existing during processing. Nowadays, the research in material engineering focuses also on modern, automatic measurement methods of joining process properties, i.a. wetting force and surface tension, which allows for quantitative determination of above mentioned parameters. In the paper, the brazes’ dynamic properties in high-temperatures’ measurement methodology and the stand for automatic determination of braze’s properties, constructed and implmented within the research grant nr KBN N N519 441 839 - An integrated platform for automatic measurement of wettability and surface tension of solders at high temperatures, are widely described

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