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Electromagnetics and Photonics

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Articles 811 - 819 of 819

Full-Text Articles in Physics

The Resistivity Of Lanthanum, Cerium, Praseodymium And Neodymium At Low Temperatures , Nancy Rennie James Jan 1952

The Resistivity Of Lanthanum, Cerium, Praseodymium And Neodymium At Low Temperatures , Nancy Rennie James

Retrospective Theses and Dissertations

No abstract provided.


Spectrochemical Analysis Of Fruit Tissue For Lead , Verlee Enid Sater Jan 1944

Spectrochemical Analysis Of Fruit Tissue For Lead , Verlee Enid Sater

Retrospective Theses and Dissertations

No abstract provided.


Measurement Of Cathode Emission By Use Of The Electron Microscope , Francis Meade Bailey Jan 1940

Measurement Of Cathode Emission By Use Of The Electron Microscope , Francis Meade Bailey

Retrospective Theses and Dissertations

The electron emission from cathode surfaces changes rapidly with temperature. The difficulty of measuring the true temperature of surfaces such as that of Barium or strontium oxide has led to the development of a comparison method in which two or more materials may be heated under identical conditions. An electron micro-scope system was used to segregate the emission from each material, the current density measurement being made photographically;Curves for Dushman's equation were plotted as a check on the reliability of the method. The apparatus was used to prepare a table of the relative emission obtained from a few ...


Breakdown Potentials Of Gases Under Alternating Voltages , David Oren Mccoy Jan 1938

Breakdown Potentials Of Gases Under Alternating Voltages , David Oren Mccoy

Retrospective Theses and Dissertations

This investigation was devoted to a study of the starting potentials of gases of commercial purity for frequencies less than one million cycles per second. The gases used were Hydrogen, Nitrogen, Helium, and Argon. The discharge tube was of spherical design having spherical aluminum electrodes three-fourths inch to diameter. Five gap distances were used ranging from 10 mm to 50 mm;The results of the investigation show that: (1) The effect of impurities in the gas pointed out by J. Thomson were not observed. (2) The usual straight line portion of the curves of Vs versus pressure were observed to ...


High Frequency Glow Discharge With Internal Electrodes , Nathan Theodore Burdine Jan 1937

High Frequency Glow Discharge With Internal Electrodes , Nathan Theodore Burdine

Retrospective Theses and Dissertations

This thesis was a quantitative study of the variation in intensities of certain lines in the hydrogen spectrum as a function of excitation frequency and pressure when internal electrodes were used. The high frequency voltage was applied to the gas by the connection of a push-pull oscillator to internal carbon electrodes. The gas system was designed to obtain spectroscopically pure hydrogen. The logarithmic sector method was used to measure the intensities of the spectrum lines, and a cathode ray oscillograph was used to measure the potential difference between the electrodes;The spectrograms were taken for pressures ranging from .005 to ...


Blackening Of Photographic Materials By Means Of Low Voltage Cathode Rays , Allan Reedy Brown Jan 1935

Blackening Of Photographic Materials By Means Of Low Voltage Cathode Rays , Allan Reedy Brown

Retrospective Theses and Dissertations

Work undertaken was to determine the effect of cathode rays photographic materials. It was desired to find the relations between the voltage of the cathode rays and blackening, and the total charge received by the film and the blackening;Special apparatus was designed for carrying out this work, exposures being made a specially constructed vacuum chamber of brass. The apparatus differed from apparatus previously used for this type of work in that a special camera was provided which made exposures on a film moving past a slit through which the electrons entered the camera. The slit was half v-shaped, giving ...


Recording Of Low Voltage Cathode Rays On Metal Films , Joseph Bion Philipson Jan 1933

Recording Of Low Voltage Cathode Rays On Metal Films , Joseph Bion Philipson

Retrospective Theses and Dissertations

No abstract provided.


The Determination Of The Thermionic Work Function Of Nickel By A New Method , Robert Mcneil Bowie Jan 1933

The Determination Of The Thermionic Work Function Of Nickel By A New Method , Robert Mcneil Bowie

Retrospective Theses and Dissertations

I. The work function of nickel was determined thermionically and found to be 5.03 +/- .05 volts. The constant A was found to be 1.38 x 103 amps/cm2deg 2;II. A new method was developed for determining the thermionic work function of metals. It differs from the conventional method in the following respects: (1) The metal is in the form of a rough sphere. (2) It is heated by electron bombardment from an auxiliary filament. (3) Measurements are made as the metal cools. (4) The emission current charges a condenser which is discharged through a galvanometer at pre-determined ...


A Magneto-Optic Method Of Determining The Vitamin Content Of Various Substances , Gerrit Martin Wissink Jan 1933

A Magneto-Optic Method Of Determining The Vitamin Content Of Various Substances , Gerrit Martin Wissink

Retrospective Theses and Dissertations

In this investigation the magneto-optic apparatus was used. This apparatus was modified to some extent from the original apparatus used by Allison. The modifications included a mercury vapor arc and a monochromator to furnish a steady source of monochromatic light, as well as a photoelectric cell circuit and amplifier to read the minima. Only half of the bilateral trolley system used by Allison was employed;The apparatus gave evidence of a distinct minimum which seemed characteristic of vitamin A. This minimum was located at 32.90 on the light path scale. Pure carotene did not give this minimum. Pure carotene ...