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Full-Text Articles in Physics

Effect Of Uniaxial Stress On The Unstable A1 (To) Phonon In Ferroelectric Gadolinium Molybdate, B.N. Ganguly, Frank G. Ullman, Roger D. Kirby, J.R. Hardy Nov 1975

Effect Of Uniaxial Stress On The Unstable A1 (To) Phonon In Ferroelectric Gadolinium Molybdate, B.N. Ganguly, Frank G. Ullman, Roger D. Kirby, J.R. Hardy

Roger Kirby Publications

The effect of uniaxial stress along [100] on the unstable A1 (TO) phonon, 47 cm-1 at room temperature, in ferroelectric (<159°C) gadolinium molybdate has been studied by Raman scattering at 138, 141, 146, and 155°C. An increase in peak frequency and narrowing of the line shape is observed with increasing stress. The data are analyzed by fitting to a Lorentzian line shape. The force-constant parameter is insensitive to both stress and temperature, whereas the damping constant decreases nonlinearly with stress, approaching an asymptotic value at high stress.


Path-Integral Formulation Of Scattering Theory, Paul Finkler, C. Edward Jones, M. Misheloff Oct 1975

Path-Integral Formulation Of Scattering Theory, Paul Finkler, C. Edward Jones, M. Misheloff

Paul Finkler Papers

A new formulation of nonrelativistic scattering theory is developed which expresses the S matrix as a path integral. This formulation appears to have at least two advantages: (1) A closed formula is obtained for the S matrix in terms of the potential, not involving a series expansion; (2) the energy-conserving δ function can be explicitly extracted using a technique analogous to that of Faddeev and Popov, thereby yielding a closed pathintegral expression for the T matrix. The introduction of the concept of the classical interaction picture provides considerable physical insight into this formulation. This formulation also suggests a successionof improvements ...


2P3/2:2P1/2 Partial Photoionization Cross-Section Ratios In The Rare Gases , James A.R. Samson, J.L. Gardner, Anthony F. Starace Oct 1975

2P3/2:2P1/2 Partial Photoionization Cross-Section Ratios In The Rare Gases , James A.R. Samson, J.L. Gardner, Anthony F. Starace

Anthony F. Starace Publications

The 2P3/2:2P1/2 partial photoionization cross-section ratios have been measured for the rare gases in the ionization continuum and within resonance structure. The wavelength range for this study was from the 2P1/2 ionization threshold to 304 Å. The ratio of the cross sections was found to be constant over this wavelength range, yielding ratios of 1.54, 1.77, 1.93, and 2.18 for Xe, Kr, Ar, and Ne, respectively. Within resonances, the ratio changed dramatically. Results are illustrated for xenon.


Technique For Rapid Faraday Susceptibility Measurements, F.R. Szofran, W.L. Burmester, David J. Sellmyer, L.G. Rubin Sep 1975

Technique For Rapid Faraday Susceptibility Measurements, F.R. Szofran, W.L. Burmester, David J. Sellmyer, L.G. Rubin

David Sellmyer Publications

An apparatus is described which permits the rapid acquisition and computer analysis of temperature-dependent Faraday susceptibility data. The apparatus utilizes a relatively inexpensive, three-channel, data-acquisition system. Review of Scientific Instruments is copyrighted by The American Institute of Physics.


Gauge Invariance And Radiative Transition Probabilities, Ian P. Grant, Anthony F. Starace Aug 1975

Gauge Invariance And Radiative Transition Probabilities, Ian P. Grant, Anthony F. Starace

Anthony F. Starace Publications

The relationship between recommendations of some recent papers on the choice of formula (length, velocity, or acceleration type) for calculating radiative transition probabilities is clarified.


Teaching-The Purpose Of Repeatable Testing: Response To Comment Of J. D. Edmonds, D.E. Golden, Robert Fuller, D.D. Jensen Aug 1975

Teaching-The Purpose Of Repeatable Testing: Response To Comment Of J. D. Edmonds, D.E. Golden, Robert Fuller, D.D. Jensen

Robert G. Fuller Publications and Presentations

It is not clear that the comment "Grading and Regrading"' has very much to do with our article.' The comment seems rather to be a nostalgic statement recalling the good old days when with glee we cracked the whip and the students either shaped up or shipped out.

Our purpose in doing repeatable testing was not to become a "do your own thing" force, to raise everyone's grades, to "achieve well defined educational objectives" like teaching the solution to the inclined plane problem, to do away with certification, and most definitely our purpose was not to replace teachers with ...


Effect Of Elliptically Polarized Light On The Angular Distribution Of Photoelectrons, James A. R. Samson, Anthony F. Starace Aug 1975

Effect Of Elliptically Polarized Light On The Angular Distribution Of Photoelectrons, James A. R. Samson, Anthony F. Starace

Anthony F. Starace Publications

The angular distribution of photoelectrons predicted for elliptically polarized light is shown to be the same as that predicted for partially polarized light having incoherent perpendicular electric field components equal to the electric field components along the major and minor axes of the ellipse.

Includes Corrigendum from J. Phys. B: Atom. Molec. Phys. 12:23 (1979), p. 3993.


Theoretical Study Of Impurity-Induced First-Order Raman Spectra For The Alkali Halides, Arnold Karo, John R. Hardy Jul 1975

Theoretical Study Of Impurity-Induced First-Order Raman Spectra For The Alkali Halides, Arnold Karo, John R. Hardy

John R. Hardy Papers

A deformation-dipole model with first- and second-neighbor central short-range forces is used as a basis for calculating all symmetry-adapted combinations of eigenvectors (SACEV) necessary for the study of defect vibrations in alkali-halide crystals. As an example of the full set of spectral weight functions, which are tabulated separately, sample results are given for the predicted defect-activated E, Raman spectra for KC1, KI, RbCl, and KBr, assuming no force-constant changes and that the defect is located at a positive-ion site. The results show qualitative agreement with the earlier findings of Harley, Page, and Walker, even though the deformation-dipole model is not ...


Theoretical Study Of Impurity-Induced First-Order Raman Spectra For The Alkali Halides, Arnold Karo, John Hardy Jul 1975

Theoretical Study Of Impurity-Induced First-Order Raman Spectra For The Alkali Halides, Arnold Karo, John Hardy

John R. Hardy Papers

A deformation-dipole model with first- and second-neighbor central short-range forces is used as a basis for calculating all symmetry-adapted combinations of eigenvectors (SACEV) necessary for the study of defect vibrations in alkali-halide crystals. As an example of the full set of spectral weight functions, which are tabulated separately, sample results are given for the predicted defect-activated E, Raman spectra for KCl, KI, RbCl, and KBr, assuming no force-constant changes and that the defect is located at a positive-ion site. The results show qualitative agreement with the earlier findings of Harley, Page, and Walker, even though the deformation-dipole model is not ...


Path Integrals With Arbitrary Generators And The Eigenfunction Problem, William B. Campbell, Paul Finkler, C. E. Jones, M. N. Misheloff Jun 1975

Path Integrals With Arbitrary Generators And The Eigenfunction Problem, William B. Campbell, Paul Finkler, C. E. Jones, M. N. Misheloff

Paul Finkler Papers

We generalize the path integral formalism of quantum mechanics to include the use of arbitrary infinitesimal generators, thus providing explicit expressions for solutions of a wide class of differential equations. In particular, we develop a method of calculating the eigenfunctions of a large class of operators.


Effects Of Anisotropic Electron-Ion Interactions In Atomic Photoelectron Angular Distributions, Dan Dill, Anthony F. Starace, Steven T. Manson May 1975

Effects Of Anisotropic Electron-Ion Interactions In Atomic Photoelectron Angular Distributions, Dan Dill, Anthony F. Starace, Steven T. Manson

Anthony F. Starace Publications

The photoelectron asymmetry parameter β in LS coupling is obtained as an expansion into contributions from alternative angular-momentum transfers jt. The physical significance of this expansion of β is shown to be that (i) the electric-dipole interaction transfers to the atom a characteristic single angular momentum jt=l0, where l0 is the photoelectron's initial orbital momentum, whereas (ii) angular-momentum transfers jtl0 indicate the presence of anisotropic (i.e., term-dependent) interaction of the outgoing photoelectron with the residual ion. For open-shell atoms the photoelectron-ion interaction is generally anisotropic; photoelectron phase shifts and electric-dipole ...


Rbe-Dose Relations For Neutrons And Pions, Robert Katz, S. C. Sharma May 1975

Rbe-Dose Relations For Neutrons And Pions, Robert Katz, S. C. Sharma

Robert Katz Publications

RBE-Dose relations have been calculated from cellular radiosensitivity parameters and theoretical particle-energy spectra in tissue, of the secondary particles from neutron and negative pion irradiations. The theoretical results are compared with clinical and radiobiological data for normal tissue, tumors, and cells in culture. Formulae for calculation, cellular parameters, and the needed properties of equivalent “track-segment bombardments” are given, for several mammalian cells irradiated with pions and with neutrons of several energies.

Résumé
Rapports EBR-dose pour neutrons et pions
A partir des paramètres de la radiosensitivité cellulaire et du spectre théorique, dens le tissu, de l’énergie d’atomes secondaires provenant ...


0 Introduction To Study Modules For Calculus-Based General Physics Jan 1975

0 Introduction To Study Modules For Calculus-Based General Physics

Calculus-Based General Physics

These modules were prepared by fifteen college physics professors for use in self-paced, mastery-oriented, student-tutored. calculus-based general physics courses. This style of teaching offers student's a personalized system of instruction (PSI), in which they increase their knowledge of physics and experience a positive learning environment. We hope our efforts in preparing these modules will enable you to try and enjoy teaching physics using PSI.

This is the second printing of the CBP modules. We have tried to remove all of the errors from this material. No doubt, we missed a few, please write to us and tell us any ...


Alternating-Current Circuits Jan 1975

Alternating-Current Circuits

Calculus-Based General Physics

The electric clock on the wall, radio and television, the incredibly rapid handling
of information by computers, and the transmission of signals by our own nerves
are among countless devices and effects that depend on circuits in which currents
or voltages vary with time. Alternatinq-current (ac) circuits, in which charges
oscillate back and forth in a wire in such a way that the average current is
zero,are among the simpler time-varying circuits. In this module you will study
the behavior of simple ac circuits containing resistors, inductors, and capacitors.


Ampère's Law Jan 1975

Ampère's Law

Calculus-Based General Physics

Everyone has seen a bar magnet in the form of a compass or a door catch. Anyone who has ever casually played with magnets or magnetic toys knows that magnets interact with other magnets; i.e., a magnet experiences a force caused by thp presence of an external magnetic field produced by the other magnet. A wire carrying a current experiences a force caused by the presence of a nearby magnet (as you saw in the module Magnetic Forces). We then expect the converse to also hold true, i.e., that the bar magnet will also experience a force from ...


Applications Of Newton's Laws Jan 1975

Applications Of Newton's Laws

Calculus-Based General Physics

Perhaps at some time you have had occasion to swing a massive object at the end of a rope. Maybe you have watched a parent swing a child around by his outstretched arms or have been fortunate enough to watch an athlete throw the hammer. But all of you have heard or watched an automatic washer go through a spin-dry cycle. How was this spinning drum with holes in its periphery able to speed up the "drying" process? The clothes were too large to pass through the holes in the drum and were "held" in a circular path but the ...


Capacitors Jan 1975

Capacitors

Calculus-Based General Physics

Capacitors are important components of electronic circuits and of electrical machinery and power grids. You can find large oil-insulated capacitors on powerline poles or small ceramic-insulated capacitors in a radio. In each application the capacitor is used to store electrical charge and electrical energy - for example, sometimes for a short time in an alternating-current cycle, sometimes for a long time until the energy is needed, as in a strobe light for a camera. Your body can be a capacitor, storing up enough charge and energy to cause a painful spark when the capacitor discharqes.

Practical capacitors are basically two conducting ...


Collisions Jan 1975

Collisions

Calculus-Based General Physics

If you have ever watched or played pool, football, baseball, soccer, hockey, or been involved in an automobile accident you have some idea about the results of a collision. We are interested in studying collisions for a variety of reasons. For example, you can determine the speed of a bullet by making use of the physics of the collision process. You can also estimate the speed of an automobile before the accident by knowing the physics of the collision process and a few other physical principles. Physicists use collisions to determine the properties of atomic and subatomic particles. Essentially, a ...


Conservation Of Energy Jan 1975

Conservation Of Energy

Calculus-Based General Physics

Imagine a bicycle rider coasting without pedaling along a road that is very smooth but has a lot of small hills. As he coasts up a hill, the force of gravity will, of course, slow him down; but it speeds him up again as he goes down the other side. We say that gravity is a conservative force because it gives back as much kinetic energy (KE) to the cyclist when he returns to a lower level, as it took away when he ascended to the top. We therefore assign a gravitational potential energy (PE) Ug to the cyclist ...


Coulomb's Law And The Electric Field Jan 1975

Coulomb's Law And The Electric Field

Calculus-Based General Physics

This module beqins the study of electricity. Not only is it true that we see nature's gigantic electrical show in thunderstorm displays with lightning, but the very functioning of our smallest cells depends on the balance of electrically charged ions, and their movement through cell membranes. On a larger scale than cell membranes, water-purification studies with large membranes show promise of "electrically" removing undesired ions or debris from water. The electronic air cleaner is yet another direct application of the material to come: a 7000-V potential difference between a thin wire and flat collecting plates ionizes the air, and ...


Diffraction Jan 1975

Diffraction

Calculus-Based General Physics

Have you ever wondered why you can hear around corners, but cannot see around them? You know that light and sound are waves, and should therefore share the same basic properties. Why then do they seem so different in the property of their "shadows"?

In this module you will learn that light does exhibit all the bending properties of sound and water waves. The effect, however, depends on the size of the obstacle compared to the wavelength. It is only the largeness of everyday obstacles compared to the very small wavelength of light that deemphasizes the bending, or diffraction, of ...


Direct-Current Circuits Jan 1975

Direct-Current Circuits

Calculus-Based General Physics

One way to help you understand a new phenomenon is to show you that it is like something that you are already familiar with. This method is used very frequently in physics, e.g., the electric field is like the gravitational field. This module will introduce you to a simple class of RC circuits in which there are currents, charges, and voltages that decay exponentially. This may be your first detailed study of exponential decay, but it is like (analagous to) radioactive decay, Newton's law of cooling, the final depletion of a natural resource, the decrease in atmospheric pressure ...


Electric Fields And Potentials From Continuous Charge Distributions Jan 1975

Electric Fields And Potentials From Continuous Charge Distributions

Calculus-Based General Physics

Too bad! In case you have not realized it, not all charges come packaged as points, spheres, infinite cylinders, or infinite planes. Ah, if only it were so: Life would be much easier from a calculational viewpoint, although somewhat limited in geometrical options. But then, mechanics would be simpler if only constant accelerations were observed in nature ... Not to mention centers of mass; moments of inertia, etc.; all would be considerably simpler to calculate in that wonderful world of point masses, constant accelerations, massless strings, and frictionless boards.

Once again calculus is needed to assist us in analyzing and understanding ...


Electric Potential Jan 1975

Electric Potential

Calculus-Based General Physics

You have no doubt noticed that TV sets, light bulbs, and other electric appliances operate on 115 V, but electric ovens and clothes dryers usually need 220 V. Batteries may be rated at a harmless 1.5, 6, 9, or 12 V, but a high-tension electric transmission line may provide electric power at 400,000 V. Now just what physical quantity is measured by all these volts? How do volts relate to force, energy, and power, about which you have learned in earlier modules? The answer is that volts measure electric potential difference (sometimes called "voltage"), which is derived from ...


Faraday's Law Jan 1975

Faraday's Law

Calculus-Based General Physics

Consider the electric light you may be using to read this module by and the influence on your life style of the vast amounts of electrical energy produced in the United States. This module treats the fundamental principle that allows for the transformation of mechanical energy into electrical energy. The physical law that governs the production of electric current is named after its discoverer, Michael Faraday.


Equilibrium Of Rigid Bodies Jan 1975

Equilibrium Of Rigid Bodies

Calculus-Based General Physics

Most of the objects that one sees are in a state of equilibrium, that is, at rest or in a state of uniform motion. Many man-made structures are designed to achieve and sustain a state of equilibrium, and this, in turn, sets requirements to the materials (their sizes and shapes) that can be used. This module will give you some practice in analyzing the forces that result in equilibrium. From this analysis, if you are given the values of an appropriate set of forces you can find the remaining ones. On the other hand, in designing a stable system you ...


Fluid Mechanics Jan 1975

Fluid Mechanics

Calculus-Based General Physics

An invigorating shower in the morning is usually a pleasant experience except for the pesky shower curtain slapping your legs and allowing water to run on the floor. You would think that the downward stream of water would be enough to keep the curtain back even without water striking the curtain. But not so: fast-moving fluids (water spray causing a downdraft of air) contain a low-pressure region. Thus the pressure outside the shower is greater than the pressure inside - with the result that the curtain is blown in and flops against your legs.

More technical applications of fluid mechanics include ...


Flux And Gauss' Law Jan 1975

Flux And Gauss' Law

Calculus-Based General Physics

Charles Augustine de Coulomb (1736-1806) designed his famous experiment to measure the force relationships between charged bodies: Coulomb's law is the resulting empirical statement. Gauss' law (Karl Friedrich Gauss, 1777-1855), which you will learn in this module, has a more obscure origin. It was originally a mathematical theorem. Scientists in Gauss' nineteenth century were much more inclined than we are today to equate mathematical correctness with physical correctness. When it was realized that Gauss' (mathematical) theorem could be applied to the electric-field concepts of Faraday to produce Gauss' (physical) law, this extension was eagerly accepted. The origins of the ...


Gravitation Jan 1975

Gravitation

Calculus-Based General Physics

The members of the solar system -- the Sun, the Moon, and the planets -- have held a strong fascination for mankind since prehistoric times. The motions of these heavenly bodies were thought to have important specific influences on persons' lives -- a belief that is reflected even today in horoscopes and astrological publications. A revolution in man's thinking that occurred about four hundred years ago established the concept of a solar system with planets orbiting about the Sun and moons orbiting about some of the planets. Copernicus, Kepler, Galileo, and Newton were the four scientific leaders chiefly responsible for establishing this ...


Impulse And Momentum Jan 1975

Impulse And Momentum

Calculus-Based General Physics

You have already learned that you stub your toe harder trying to kick larger masses. Now imagine another unpleasant activity: catching a bowling ball. This gets harder to do as the ball is dropped from higher places. The difficulty depends both on the ball's mass and its velocity just before you apply the stopping force. This force can be applied in different ways. Any winner of an egg-throwing contest will tell you the way to stop an object with the least force is to spread the stopping process out over a maximum time.

This module will develop the above ...