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Full-Text Articles in Physics
Structure Of Ch2, Gordon A. Gallup
Structure Of Ch2, Gordon A. Gallup
Gordon Gallup Publications
Gray has criticized the calculation of the ground state multiplicity of the CH2 fragment by the author. In answer, I would like to make two comments.
1. Regardless of the energies of ionization of a carbon atom, CH2 may be considered as a system composed of two protons, a carbon kernel, and four electrons. The proper amount of configuration interaction should arise naturally and depend on relative energies of orbitals and overlap values. It appears that there is too much configuration interaction in the calculation in reference since the equilibrium angle arrived at is 160° instead of 140° …
Physics, Contents, Henry Semat, Robert Katz
Physics, Contents, Henry Semat, Robert Katz
Robert Katz Publications
Table of contents
Physics, Chapter 1: Fundamental Quantities, Henry Semat, Robert Katz
Physics, Chapter 1: Fundamental Quantities, Henry Semat, Robert Katz
Robert Katz Publications
Physics is a fundamental science dealing with matter and energy. By convention, the subject matter of physics has been divided into such topics as mechanics, heat, sound, light, and electricity. In addition to these general classifications, present-day physics includes atomic physics, nuclear physics, solid-state physics, chemical physics, biophysics, and many other subdivisions. It is impossible to include all aspects of physics in a single definition or paragraph, and to distinguish physics clearly from its nearest neighbors, the other physical sciences-astronomy., chemistry, and geology.
Physics, Chapter 7: Work And Energy, Henry Semat, Robert Katz
Physics, Chapter 7: Work And Energy, Henry Semat, Robert Katz
Robert Katz Publications
An extremely important concept that has been developed in physics is that of the work done on a body by the action of some external agent which exerts a force on this body and produces motion. For example, whenever someone lifts a body, he does work by exerting a force upward on it and moving it upward. Whenever a steam locomotive pulls a train, a series of processes takes place in the steam engine of the locomotive which enables it to exert a force on the train and move it in the direction of the force. The term work, as …
Physics, Chapter 5: Force And Motion, Henry Semat, Robert Katz
Physics, Chapter 5: Force And Motion, Henry Semat, Robert Katz
Robert Katz Publications
All of us have many times had the experience of setting a body in motion. If we analyze any of these experiences, we readily recall that in each case some force was required to start the object moving. In throwing a ball, moving a piece of furniture, or pulling a sled, the force needed to start the object moving is supplied by one's muscular effort as a push or a pull. In more complex cases, such as setting a car or an airplane in motion, the analysis, although more complicated, will also show that a force is required to start …
Physics, Chapter 6: Circular Motion And Gravitation, Henry Semat, Robert Katz
Physics, Chapter 6: Circular Motion And Gravitation, Henry Semat, Robert Katz
Robert Katz Publications
Our earlier discussion of the kinematics of a particle was developed principally from the point of view of being able to describe that motion easily within a rectangular coordinate system. Thus the most complex case with which we dealt was that of a projectile motion, in which the acceleration was constant and was directed along one of the coordinate axes. A more convenient framework within which to discuss rotational and circular motions is provided by a set of polar coordinates. In the present discussion we will restrict ourselves to motion in which the polar coordinate r is constant, or fixed; …
Physics, Chapter 8: Hydrostatics (Fluids At Rest), Henry Semat, Robert Katz
Physics, Chapter 8: Hydrostatics (Fluids At Rest), Henry Semat, Robert Katz
Robert Katz Publications
From our everyday experience, we have become familiar with the fact that matter occurs in three different forms-solid, liquid, and gas. Under ordinary conditions stone, iron, copper, and chalk, for example, are solids; water, oil, and mercury are liquids; air, hydrogen, and carbon dioxide are gases. Each one of these forms is called a phase. At times it is difficult to distinguish clearly between the solid and the liquid phases, as in a material such as tar which flows under the action of a force at ordinary temperatures. Metals at high temperatures flow or "creep" under the action of a …
Physics, Chapter 10: Momentum And Impulse, Henry Semat, Robert Katz
Physics, Chapter 10: Momentum And Impulse, Henry Semat, Robert Katz
Robert Katz Publications
An extremely important concept in the development of mechanics is that of momentum. The momentum of a body is defined as the product of its mass by its velocity. We shall use the symbol p to denote the momentum of a body. The momentum of a body is a vector quantity, for it is the product of mass, a scalar, by velocity, a vector. While momentum and kinetic energy are compounded of the same two ingredients, mass and velocity, they are quite different concepts, and one aspect of their difference may be seen in the fact that momentum is …
Physics, Chapter 13: Properties Of Matter, Henry Semat, Robert Katz
Physics, Chapter 13: Properties Of Matter, Henry Semat, Robert Katz
Robert Katz Publications
When a system is subjected to external forces, it generally undergoes a change in size or shape or both. We have thus far touched very lightly on such changes; for example, we have considered the change in length of an elastic spring and the change in volume of a gas when such systems were subjected to varying pressures. The changes produced in a system by the action of external forces depend upon the physical properties of the material of which the system is composed. A study of the properties of matter leads to information which is of practical value to …
Physics, Chapter 14: Temperature, Henry Semat, Robert Katz
Physics, Chapter 14: Temperature, Henry Semat, Robert Katz
Robert Katz Publications
Temperature is one of the fundamental concepts of physics. We are all able to recognize that some bodies are hotter than others, but our temperature sense is qualitative rather than quantitative and is capable of only a limited range. The sense of touch can frequently be used to distinguish between hotter and colder objects, provided that these lie in a temperature range consistent with the stability of human tissue. Even within this range the sense of touch is often unreliable as a measure of temperature.
The metal bracket holding a wooden rail may feel much colder to the touch than …
Physics, Chapter 17: The Phases Of Matter, Henry Semat, Robert Katz
Physics, Chapter 17: The Phases Of Matter, Henry Semat, Robert Katz
Robert Katz Publications
A substance which has a definite chemical composition can exist in one or more phases, such as the vapor phase, the liquid phase, or the solid phase. When two or more such phases are in equilibrium at any given temperature and pressure, there are always surfaces of separation between the two phases.
In the solid phase a pure substance generally exhibits a well-defined crystal structure in which the atoms or molecules of the substance are arranged in a repetitive lattice. Many substances are known to exist in several different solid phases at different conditions of temperature and pressure. These …
Physics, Chapter 18: Transfer Of Heat, Henry Semat, Robert Katz
Physics, Chapter 18: Transfer Of Heat, Henry Semat, Robert Katz
Robert Katz Publications
The methods by which heat is transmitted can be classified into three distinct types known as convection, conduction, and radiation. In any actual case of heat transmission, a combination of these methods may be operating simultaneously, and the principal problem is to determine the rate at which heat flows from the source at higher temperature to the source at lower temperature.
We may distinguish between the three processes of heat transfer by considering whether a medium is required for the transfer of heat, and whether that medium is at rest or in motion. In the process of conduction, …
Physics, Chapter 19: Heat Engines, Henry Semat, Robert Katz
Physics, Chapter 19: Heat Engines, Henry Semat, Robert Katz
Robert Katz Publications
In this chapter we shall consider the physical principles underlying the operations of heat engines because of the intrinsic importance of these principles and because of the part they have played in the development of fundamental physical ideas. Heat engines are designed and built to convert heat into work. In most cases the heat is obtained from the combustion of a common fuel such as coal, oil, gasoline, or natural gas. An important new source of heat that is just beginning to be used, and will be used more extensively in the future, is the mass which is converted into …
Physics, Chapter 20: Wave Motion, Henry Semat, Robert Katz
Physics, Chapter 20: Wave Motion, Henry Semat, Robert Katz
Robert Katz Publications
Wave motion is an important method of transferring energy from one place to another without involving the actual transfer of matter. When a pebble is dropped into a still pool, some of the kinetic energy of the pebble is used to generate the ripples which spread out in all directions over the surface of the pool. When the ripples pass by a floating object, such as a bit of cork, the cork bobs up and down, having acquired its kinetic energy of vibration from the ripple system. The ripples thus serve to deliver some of the energy of the pebble …
Physics, Chapter 22: Electrostatics, Henry Semat, Robert Katz
Physics, Chapter 22: Electrostatics, Henry Semat, Robert Katz
Robert Katz Publications
One simple phenomenon of electricity was known to the ancients: that when a piece of amber was rubbed, it acquired the property of attracting small pieces of paper and other light particles. Records show that Thales of Miletus (circa sixth century B.C.) knew of this property of amber; the Greek word for amber is elektron, hence the name electricity. There was practically no further development of this subject until about the seventeenth century. Otto von Guericke (1602-1686) of Magdeburg built a large sulphur sphere, which, when rotated about an axis and rubbed with his hand, gave off electric sparks. In …
Physics, Chatper 24: Potential, Henry Semat, Robert Katz
Physics, Chatper 24: Potential, Henry Semat, Robert Katz
Robert Katz Publications
A positive charge q situated at some point A in an electric field where the intensity is E will experience a force F given by Equation (23-1a) as F = Eq. In general, if this charge q is moved to some other point B in the electric field, an amount of work ΔW will have to be performed. The ratio of the work done ΔW to charge q transferred from point A to point B is called the difference of potential ΔV between these points.
Physics, Chapter 26: The Electric Current, Henry Semat, Robert Katz
Physics, Chapter 26: The Electric Current, Henry Semat, Robert Katz
Robert Katz Publications
Electricity is the basis of our present highly technical civilization. It is the means whereby energy from various sources is delivered to the consumer in a form suitable for its conversion into the many kinds of energy demanded by him. It is through the intermediary of the electric circuit that energy is transmitted electrically from the primary source, no matter where it is situated, to the ultimate consumer wherever he desires it. A complete electric circuit contains some form of electric generator, which is essentially a device for converting other forms of energy to electrical energy, a set of conductors …
Physics, Chapter 30: Magnetic Fields Of Currents, Henry Semat, Robert Katz
Physics, Chapter 30: Magnetic Fields Of Currents, Henry Semat, Robert Katz
Robert Katz Publications
The first evidence for the existence of a magnetic field around an electric current was observed in 1820 by Hans Christian Oersted (1777-1851). He found that a wire carrying current caused a freely pivoted compass needle in its vicinity to be deflected. If the current in a long straight wire is directed from C to D, as shown in Figure 30-1, a compass needle below it, whose initial orientation is shown in dotted lines, will have its north pole deflected to the left and its south pole deflected to the right. If the current in the wire is reversed and …
Physics, Chapter 29: The Magnetic Field, Henry Semat, Robert Katz
Physics, Chapter 29: The Magnetic Field, Henry Semat, Robert Katz
Robert Katz Publications
Natural magnets, called lodestones, have been known since ancient times. The lodestone, a magnetic oxide of iron called magnetite (Fe3O4), was mentioned by Thales of Miletus. By the eleventh century the magnetic compass was known to the Chinese, and in the twelfth century references to the compass were made in Western Europe. The lodestone is capable of attracting pieces of iron and of imparting permanent magnetism to other pieces of iron so that these too could attract iron filings. If an iron bar is magnetized, as the result of being near a piece of lodestone, and …
Physics, Chapter 33: Magnetic Properties Of Matter, Henry Semat, Robert Katz
Physics, Chapter 33: Magnetic Properties Of Matter, Henry Semat, Robert Katz
Robert Katz Publications
Matter is composed of atoms consisting of positively charged nuclei and negative electrons. These electrons occur in shells, and the periodic nature of chemical properties of atoms as the atomic weight increases is a reflection of the fact that the chemical behavior of an atom depends largely upon the number of electrons in the outermost shell. In some parts of the periodic table (see Table 5 of Appendix A), electrons occupy places in an outer shell before an inner shell is completely filled; it is then observed that a number of different elements have very similar chemical properties. The same …
Physics, Chapter 32: Electromagnetic Induction, Henry Semat, Robert Katz
Physics, Chapter 32: Electromagnetic Induction, Henry Semat, Robert Katz
Robert Katz Publications
When a wire moves through a uniform magnetic field of induction B, in a direction at right angles to the field and to the wire itself, the electric charges within the conductor experience forces due to their motion through this magnetic field. The positive charges are held in place in the conductor by the action of interatomic forces, but the free electrons, usually one or two per atom, are caused to drift to one side of the conductor, thus setting up an electric field E within the conductor which opposes the further drift of electrons. The magnitude of this …
Physics, Chapter 34: Alternating Currents, Henry Semat, Robert Katz
Physics, Chapter 34: Alternating Currents, Henry Semat, Robert Katz
Robert Katz Publications
If the current in a resistor varies sinusoidally, as shown in Figure 34-1, the potential difference across the terminals of the resistor will also vary sinusoidally in the same manner, in phase with the current, in accordance with Ohm's law. Writing i for the instantaneous value of the current and v for the instantaneous value of the potential difference, we have v = iR.
Physics, Chapter 37: Reflection And Refraction, Henry Semat, Robert Katz
Physics, Chapter 37: Reflection And Refraction, Henry Semat, Robert Katz
Robert Katz Publications
In the passage of a beam of light through a medium, some of the radiant energy is absorbed and is transformed into internal energy, while some of it is scattered in all directions. The oscillating electric field associated with the light wave sets some of the electrons of the medium into oscillation, thus giving up some of its energy, and these oscillating electrons subsequently reradiate energy as scattered electromagnetic radiation. Scattering therefore takes place only in the presence of matter. The color of the sky is due to the small amount of scattering of sunlight by the molecules of the …
Physics, Chapter 38: Mirrors And Lenses, Henry Semat, Robert Katz
Physics, Chapter 38: Mirrors And Lenses, Henry Semat, Robert Katz
Robert Katz Publications
A spherical mirror consists of a small section of the surface of a sphere with one side of the surface covered with a polished reflecting material, usually silver or aluminum. If the outside, or convex surface, is silvered, we have a convex mirror; if the inside, or concave surface, is silvered, we have a concave mirror, as shown in Figure 38-1. Most mirrors used commercially are made of glass, with the rear surface silvered and then coated with a layer of paint or lacquer for protection. Mirrors for astronomical telescopes (')f other accurate scientific work are provided with a reflective …
Physics, Chapter 41: Polarized Light, Henry Semat, Robert Katz
Physics, Chapter 41: Polarized Light, Henry Semat, Robert Katz
Robert Katz Publications
The phenomena of interference and diffraction show that light is propagated as a wave motion, but they do not show whether light is a longitudinal wave or a transverse wave. The fact that the velocity of light is the same as the velocity of radio waves and the radiation of visible light from accelerated electrons, as in a betatron, indicates that light is an electromagnetic wave. We recall from Section 20-9 that a wave can be shown to be transverse if a device can be found which will prevent passage of the wave in one orientation and will allow the …
Physics, Chapter 42: Optical Spectra And Atomic Structure, Henry Semat, Robert Katz
Physics, Chapter 42: Optical Spectra And Atomic Structure, Henry Semat, Robert Katz
Robert Katz Publications
When light passes through a prism spectroscope or a diffraction-grating spectroscope, an optical spectrum is obtained in which the intensity of the radiation may be analyzed as a function of wavelength. The spectrum may be observed visually in the limited wavelength region to which the eye is sensitive; it may be focused on a photographic plate or upon a thermocouple or thermopile. Our knowledge of the structure of atoms and molecules is largely dependent upon the analyses of optical spectra, for these spectra are characteristic of the emitting atoms or molecules. Even before the spectra of atoms were properly understood …
Physics, Chapter 44: Stable Nuclei, Henry Semat, Robert Katz
Physics, Chapter 44: Stable Nuclei, Henry Semat, Robert Katz
Robert Katz Publications
Atomic and nuclear physics are essentially twentieth-century developments, although these had their origins at the close of the nineteenth century. These developments followed two parallel streams, as shown in Figure 44-1, one dealing with the electronic structure of the atom and the other dealing with its nuclear structure. These two streams served to feed each other and were fed by all other branches of physics, but only a few of the more important contributions concerning the nature of radiation, matter, and energy are shown in the figure.
Physics, Chapter 43: X-Rays, Henry Semat, Robert Katz
Physics, Chapter 43: X-Rays, Henry Semat, Robert Katz
Robert Katz Publications
The study of the electric discharge through gases led directly to the discovery of x-rays by W. C. Roentgen in 1895. While operating a gas discharge tube, Roentgen observed that a platinum-barium cyanide screen at some distance from the tube fluoresced. He shielded the tube so that no visible radiation could reach the screen, but the fluorescence could still be observed. On interposing various materials between the tube and the screen, he found that the intensity of the fluorescence could be diminished, but that it was not completely obliterated. He interpreted these observations as being due to radiation coming from …
Physics, Appendix B, Henry Semat, Robert Katz
Physics, Chapter 46: Nuclear Reactions, Henry Semat, Robert Katz
Physics, Chapter 46: Nuclear Reactions, Henry Semat, Robert Katz
Robert Katz Publications
One of the most important developments of twentieth-century physics was the formulation of the special theory of relativity. This theory was an outgrowth of the failure of all attempts to show that the motion of the source of light relative to the observer had any effect on the speed of light. It is impossible to account for these experimental findings of Michelson and Morley, and others, on the basis of classical mechanics and electromagnetic theory. In 1905, Albert Einstein put forth the suggestion that all experimental findings would be clarified if it were assumed that the speed of light is …