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Full-Text Articles in Physical Sciences and Mathematics
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 16: Kinetic Theory Of Gases, Henry Semat, Robert Katz
Physics, Chapter 16: Kinetic Theory Of Gases, Henry Semat, Robert Katz
Robert Katz Publications
The behavior of a gas under various conditions of temperature and pressure has already been studied in some detail. When the pressure of a constant mass of gas is not too great, say less than about 2 atm, we find that a gas obeys the following relationships to be discussed.
Physics, Chapter 40: Light As A Wave Motion, Henry Semat, Robert Katz
Physics, Chapter 40: Light As A Wave Motion, Henry Semat, Robert Katz
Robert Katz Publications
Let us recount some of the characteristics of the motion of particles and the propagation of waves, with a view toward analyzing the behavior of light. In accordance with Newton's first law, a particle moves in a straight-line path in the absence of external forces. Thus we might infer, as Newton suggested, that light is composed of particles, and that, in a continuous medium, there is no deflecting force on the light particles. At the interface between two media, light may be propagated in a straight line parallel to the interface. Thus even at an interface there is no force …
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 36: Light And Its Measurement, Henry Semat, Robert Katz
Physics, Chapter 36: Light And Its Measurement, Henry Semat, Robert Katz
Robert Katz Publications
The word light, as commonly used, refers to the radiant energy which produces a visual effect. It was first shown by Maxwell that light is an electromagnetic radiation, propagated with a speed whose value was numerically determined by the relationship between electric and magnetic units.
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 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 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 …
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, 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, Appendix C, Henry Semat, Robert Katz
Physics, Appendix C, Henry Semat, Robert Katz
Robert Katz Publications
Appendix C: Answers to Odd-Numbered Problems
Physics, Chapter 15: Heat And Work, Henry Semat, Robert Katz
Physics, Chapter 15: Heat And Work, Henry Semat, Robert Katz
Robert Katz Publications
Until about 1750 the concepts of heat and temperature were not clearly distinguished. The two concepts were thought to be equivalent in the sense that bodies at equal temperatures were thought to "contain" equal amounts of heat. Joseph Black (1728-1799) was the first to make a clear distinction between heat and temperature. Black believed that heat was a form of matter, which subsequently came to be called caloric, and that the change in temperature of a body when caloric was added to it was associated with a property of the body which he called the capacity. Later investigators endowed caloric …
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 39: Optical Instruments, Henry Semat, Robert Katz
Physics, Chapter 39: Optical Instruments, Henry Semat, Robert Katz
Robert Katz Publications
The photographic camera uses a converging lens to form a real, inverted image of an object. The image is focused on a film or plate which is coated with an emulsion containing silver bromide crystals. When a few incident quanta of light are absorbed in a grain of emulsion, the grain becomes activated and developable, and when the plate is developed, the bromine is removed from each activated grain, leaving a clump of silver behind. When the plate is "fixed," the remaining emulsion is removed from the plate, so that the image is made permanent. In most cameras the converging …
Physics, Chapter 23: The Electric Field, Henry Semat, Robert Katz
Physics, Chapter 23: The Electric Field, Henry Semat, Robert Katz
Robert Katz Publications
We have previously described the gravitational field as one way of thinking about gravitational forces (Section 6-16). If an object of mass m at rest at a point P experienced a force, we could attribute that force to the presence of the gravitational field. In a similar way we may attribute the force experienced by an electric charge at rest at a point P to the presence of an electric field at that point. From the preceding chapter we recognize that the existence of a force ,on a charged particle is due to the presence of other charged particles in …
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 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, Appendix A, Henry Semat, Robert Katz
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 31: Forces On Moving Charges And Currents, Henry Semat, Robert Katz
Physics, Chapter 31: Forces On Moving Charges And Currents, Henry Semat, Robert Katz
Robert Katz Publications
Ampere was the first to show that wires carrying current experienced forces when placed in magnetic fields. Later it was shown that charged particles moving in magnetic fields also experience forces. Common applications of these phenomena are the electric motor, the galvanometer, and the cathoderay tube. Since a moving electric charge is equivalent to a current, we shall first consider the force acting on a charge q moving with velocity v in a magnetic field of induction B. Experiment shows that the force F acting on the charge q is at right angles to the directions of both v and …
Physics, Chapter 35: Electronics, Henry Semat, Robert Katz
Physics, Chapter 35: Electronics, Henry Semat, Robert Katz
Robert Katz Publications
The electrons of an atom occupy certain energy levels when the atom is far from other atoms. When a large number of atoms are assembled to form a conducting metallic solid, the energy levels of the valence electrons are displaced in position to form a conduction band, as discussed in Section 28-4. The valence electrons occupy energy levels within the conduction band and are relatively free to drift from atom to atom within the metal. In accordance with a fundamental physical principle, known as the Pauli exclusion principle, only 1 electron may occupy a particular energy level. The conduction electrons …
Physics [Complete Work], Henry Semat, Robert Katz
Physics [Complete Work], Henry Semat, Robert Katz
Robert Katz Publications
This book is intended for students of science and engineering; it aims to develop both an understanding of the important concepts of physics and some analytical skill in the solutions of problems. The mathematical level of the book is such that it may be used by students who are taking a course in calculus concurrently.
The notations and methods of the calculus are introduced early in the text, beginning with the concept of a derivative in the discussion of motion, and are then extended to more complex problems as the student progresses both in physics and in mathematics. Vector algebra …