Hafez Radi

October University of Modern Sciences and Arts · Faculty of Engineering

This article proves that speed of light in all uniformly moving inertial reference frames is absolute as postulated by Einstein. This is first done by considering light propagating with a speed c in all directions in an inertial frame of reference. If that frame is moving uniformly with a speed v relative to a second stationary inertial frame, we a...

Numerical semiclassical calculations are carried out to study the angular distribution of deuterons from the p,d pickup reaction of 25 MeV protons incident on the nucleus Gd156 and also its proton elastic scattering. It is found that, due to the rapid fall of the real optical potential in the vicinity of the target nucleus, the classical trajectori...

Any object that repeats its motion at regular time intervals is said to perform a periodic or harmonic motion. If the motion is a sinusoidal function of time, we call it simple harmonic motion .

Newton’s law of gravity and Coulomb’s law of electrostatics are mathematically identical. In particular, electrostatic forces are conservative. Consequently, it is more convenient to assign an electric potential energy U to describe any system of two or more charged particles. This idea allows us to define a scalar quantity known as the electric po...

When a particle moves in a straight line, we can take its motion to be positive in one specific direction and negative in the other. However, when this particle moves in three dimensions, plus or minus signs are no longer enough to specify the direction of motion. Instead, we must use a vector.

In this chapter, we explore the phenomenon that occurs when combining two or more waves at one point in the same medium. This phenomenon is known as interference . We first combine waves having the same frequencies. Then we combine waves that have slightly different frequencies. In both cases we only consider waves with small amplitudes so that we...

The laws of physics are expressed in terms of basic quantities that require a clear definition for the purpose of measurements. Among these measured quantities are length, time, mass, temperature, etc.

Our focus in this chapter will be on the concept of internal energy, energy transfer, the first law of thermodynamics, and some applications of this law. The first law of thermodynamics expresses the general principle of conservation of energy. According to this law, an energy transfer to or from a system by either heat or work can change the inter...

In this chapter, we first treat the rotation of an extended object about a fixed axis. This is commonly known as pure rotational motion. The analysis is greatly simplified when the object is rigid. To perform this analysis, we first ignore the cause of rotation and describe the rotational motion in terms of angular variables and time. This is known...

Since ancient times, the nature and properties of light have been intensively investigated in an attempt to address many of our needs for a better life on Earth. Today, scientists view the behavior of light as waves (electromagnetic waves ) in some situations and particles (photons ) in other situations. In this chapter, we briefly introduce aspect...

In this chapter we complete the description of magnetic interactions by briefly exploring the origins of magnetic fields .

In this chapter, we introduce a physical quantity known as temperature, which is one of the seven SI base quantities. Temperature is associated with our sense of hot and cold. Physicists and engineers measure temperature more objectively using the Kelvin scale, which is independent of the properties of any substance.

In this chapter we treat light as waves to study interference, diffraction, and polarization. This study is known as wave optics or physical optics.

This chapter extends the study of the preceding chapter to two dimensions. We divide the study into two parts: motion of a particle in a plane, and circular motion of a particle in a plane.

In the previous chapter, we dealt with the kinematics and dynamics of the rotation of an extended object about a fixed axis. The rotational motion was analyzed in terms of Newton’s second law for rotation as well as rotational kinetic energy.

The kind of interaction that accelerates an object is called a force , which could be a push or pull.

In this chapter we analyze simple electric circuits that contain devices such as batteries, resistors, and capacitors in various combinations. We begin by introducing steady-state electric circuits and the concept of a constant rate of flow of electric charges, known as direct current (dc) . We also introduce Kirchhoff’s two rules , which are used...

In this chapter, we introduce the concept of an electric field associated with a variety of charge distributions. We follow that by introducing the concept of an electric field in terms of Faraday’s electric field lines. In addition, we study the motion of a charged particle in a uniform electric field.

Experimentally, M. Faraday and J. Henry show that a changing magnetic field can establish a current in a circuit that has no battery. When we move a magnet toward a stationary loop that is connected to a galvanometer, the galvanometer’s needle deflects in one direction. When the magnet stops, no deflection is observed. Now, when we move the magnet...

An emf produced by a physical source (like a battery) is quite different from that produced by changing magnetic flux. In this chapter, we study how an emf is induced as a result of a changing magnetic flux produced by the circuit itself or by a nearby circuit.

Although Coulomb’s law is the governing law in electrostatics, its form does not always simplify calculations in situations involving symmetry. In this chapter, we introduce Gauss’s law as an alternative method for calculating electric fields of certain highly symmetrical charge distribution systems. In addition to being simpler than Coulomb’s law,...

In the simplest model of an ideal gas, which was presented in the previous chapter, we consider each atom/molecule to be a hard sphere that collides elastically with other atoms/molecules or with the walls of the container holding the gas.

The physical states of matter can generally be divided into three broad classes: solids, liquids, and gases, see Fig. 10.1. A solid maintains its shape: it resists the action of external forces that tend to change its shape or volume.

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In this chapter, we introduce the linear momentum of a particle and the law of conservation of linear momentum of a system of particles under certain conditions. We use this law and the conservation of energy to analyze translational motion when particles collide. For a system of isolated particles, or an extended object, we introduce the concept o...

Sound waves are the most common examples of longitudinal waves. The speed of sound waves in a particular medium depends on the properties of that medium and the temperature. Sound waves travel through air when air elements vibrate to produce changes in density and pressure along the direction of the wave’s motion.

In this chapter we introduce capacitors, which are one of the simplest circuit elements. Capacitors are charge-storing devices that can store energy in the form of an electric potential energy, and are commonly used in a variety of electric circuits.

Work , energy , and power are words that have different meanings in our everyday life. Nevertheless, physicists give them specific definitions, which we present in this chapter. The work-energy power approach provides identical results to those obtained by Newtonian mechanics, but usually with simpler analysis, especially when dealing with complex...

Mechanics is the science that deals with motion of objects. It is basic to all other branches of physics. The branch of mechanics that describes the motion of objects is called kinematics. In this branch we answer questions like “Does the object speed up, slow down, stop, or reverse direction?” and “How is time involved in these situations?”

It is of common knowledge that every magnet attracts pieces of iron and has two poles: a north pole (N) and a south pole (S). In addition, given two magnets, like poles (N–N or S–S) repel each other, and opposite poles (N–S) attract each other. Moreover, if we cut a magnet in half, we do not obtain isolated north and south poles. Instead, we get tw...

It has been known for over two years now that the pion(-) spectrum from heavy ion collisions peaks near beam velocity and that the pion (+) spectrum has a corresponding depression. It has been guessed that these features are Coulomb effects of projectile fragments. A theoretical treatment of this phenomena is given, and results are compared with ex...

Lorentz-invariant cross sections for the production of π0, π+, and π- have been investigated, for the pion c.m. momentum range 0–0.5 GeV/c at angles 0°–90°, by Monte Carlo methods for grazing nuclear collisions of 207Pb+207Pb at 0.4 GeV/nucleon. Pions are considered to be produced isotropically at the center of mass at closest approach at random fr...

A model is presented for the scattering of obliquely incident relativistic pions from a region of uniform nuclear matter. A simple analytic method that incorporates a second order optical potential in the Klein-Gordon equation is constructed. This method gives only one physically acceptable solution for which the real and imaginary parts of the wav...

The Coulomb effects on slow pions formed in heavy ion collisions are investigated here by Monte Carlo methods. The trajectory calculations differ from some earlier theoretical work in that pions are considered to be absorbed if they pass within 0.8 radius of a spectator nuclear center. Absorption in the fireball is implicit in the treatment. The so...

To compare with the wealth of new data on alpha-accompanied fission of 236U* we have made new trajectory calculations. Initial conditions for several parameters were selected from Gaussian distributions by the Monte Carlo method and about 15 000 trajectories were run for an alpha source at the electrostatic saddle point. Momentum and energy are ful...

The discussion centers on pions in the velocity regions of target and projectile, where strong spectral features appear. The topics covered include stopped-pion studies, and convoy pions in the projectile frame. (GHT)

Coulomb effects on heavy-ion pion production cross sections are formulated in terms of weighted averaging over various projectile fragments. Satisfactory fits to zero-degree pion data are found for Ar + C and Ne + C systems. The fragment distributions of excited compound nuclei before nucleon evaporation must be used. Average charge Zeff values are...

It is shown that the rotational signatures for ground-band alpha decay can be calculated from nuclear beta2 and beta4 deformation values. The alpha-decay probability function over the nuclear surface is equated with the differences of the parent and daughter surfaces, hence with the changes in deformation parameters. It is suggested that deformatio...

Expressions for the two-electron atom wavefunctions of the various members of the helium isoelectronic sequence from Li+ to N5+, as well as He, are presented: these are applicable in physical, astrophysical and chemical problems. Most of these expressions are few-parameter wavefunctions. The parameters were chosen variationally and their values are...

A brief review of the development of α-decay-rate theory is given. Then in this paper are presented relative αdecay-rate theoretical calculations for doubly odd spherical nuclei for 212At and 212Atm α decay to excited states of 208Bi using mixed-configuration-shell-model parent and daughter wave functions and α particle approximations. Results are...

Nonrelativistic wave functions and energy values for the ground state of helium are calculated accurately by using the conventional Rayleigh-Ritz technique. However, the trial wave functions used are more general than those used by Hylleraas and others. They contain interelectronic separation coordinates in the exponential function beside the varia...

The Kohn variational method has been applied to the zero energy positron-helium collisions. Results show that singularity persists in scattering length values, for variant IV of Peterkop and Rabik (1971), which may suggest that this method is not, after all, reliable.

A Rayleigh-Ritz variational calculation, to investigate the possibility ; of existence of a positron-helium bound state, is carried out using 9 different ; trial functions containing parameters of which the number varies from 4 to 18. ; The results indicate that the positron does not get bound to a helium atom. This ; disagrees with a similar calcu...

The program ATOMINT written in FORTRAN IV for the IBM 360/30 evaluates an atomic integral containing three odd powers of interelectronic separation coordinates, which appear in bound state variational calculations of three electron atoms and in phase shift variational calculations of scattering of electrons (or positrons) by two-electron atoms....

A variational calculation with a trial wave function including up to 17 parameters has been used to investigate the existence of a positron-helium bound state. The resulting binding energy was found to be greater than the helium binding energy, and thus it is believed that the positron does not get bound to a helium atom. The calculations provide a...

The Kohn variational method with a multi-parameter trial wave function has been applied to the low-energy s-wave elastic scattering of positrons by helium atoms. The phase shifts obtained are in qualitative agreement with those obtained by other authors applying different methods. Quantitatively, the size of the phase shifts indicates that the chos...

A brief review of the development of ..cap alpha..-decay-rate theory is given. Then in this paper are presented relative ..cap alpha..-decay-rate theoretical calculations for doubly odd spherical nuclei for ²¹²At and ²¹²At/sup m/ ..cap alpha.. decay to excited states of ²°⁸Bi using mixed-configuration-shell-model parent and daughter wave...