Oh, I dunno... A few of the Deep Sea Detectives episodes look really interesting. Especially the ones with sunken caves, etc. Would like to get those when I get some more $$...Grey Cloud wrote:Hey congratulations, you appear to have discovered a way of making televisions interesting and educational which is more than the media corporations have done in over half a century.
Great stuff! I think I'll slap that over into the resources thread as an educational resource!StefanR wrote:http://www.matter.org.uk/Schools/Conten ... efault.htmthe magnetic field resulting from a current flowing in:
a straight wire;
a circular coil; and
a solenoid.
I am watching the series with the knowledge of APM and the EU. Video one has some interesting points of relationship.junglelord wrote:Video lecture series on electricity and magnatism from MIT
http://ocw.mit.edu/OcwWeb/Physics/8-02E ... /index.htm
The ability to point to something connecting the two constants is good, the dismissal of the Coulomb constant as nothing beautiful and to just forget the 4pi Epsolom 0, is really sad. Thats at 33 minutes.There is an enormous amount of force in the Gforce, derived from Coulombs Electostatic constant, from Newtons Gravitational constant, and from the newly defined Aether unit constant known as the rotating magnetic field unit of measurement, or the Aether Electromagnetic constant
These three manifestations of Gforce directly relate to the three force carries. Electrostatic charge, electromagnetic charge, and the mass within primary angular momentum. The Coulomb electrostatic constant is the interaction constant of the Gforce with electrostatic charge. The unit of rotating magnetic field is the interaction constant of the Gforce with electomagnetic charge. And Newtons gravitational constant is the interaction constant of the Gforce with mass.
Although he's a fellow dutchman (Watch him talk about the relative strength of the forces and then watch him totally dispel any belief that space has any electric forces that quantify, then watch him proclaim space is gravity centered.....man it really bites. This begins at 37 minutes. This is MIT and this is EM science? He totally and inadequatly dispelled any further thought of charge in space as meaningfull in the first lecture. Incredible.
typical dutch accent) , he's is a sort of gatekeaper obliged to give the consensus theories. http://www.aip.org/history/electron/jjhome.htmDo atoms have parts? J.J. Thomson suggested that they do. He advanced the idea that cathode rays are really streams of very small pieces of atoms. Three experiments led him to this.:
First, in a variation of an 1895 experiment by Jean Perrin, Thomson built a cathode ray tube ending in a pair of metal cylinders with a slit in them. These cylinders were in turn connected to an electrometer, a device for catching and measuring electrical charge. Perrin had found that cathode rays deposited an electric charge. Thomson wanted to see if, by bending the rays with a magnet, he could separate the charge from the rays. He found that when the rays entered the slit in the cylinders, the electrometer measured a large amount of negative charge. The electrometer did not register much electric charge if the rays were bent so they would not enter the slit. As Thomson saw it, the negative charge and the cathode rays must somehow be stuck together: you cannot separate the charge from the rays.
All attempts had failed when physicists tried to bend cathode rays with an electric field. Now Thomson thought of a new approach. A charged particle will normally curve as it moves through an electric field, but not if it is surrounded by a conductor (a sheath of copper, for example). Thomson suspected that the traces of gas remaining in the tube were being turned into an electrical conductor by the cathode rays themselves. To test this idea, he took great pains to extract nearly all of the gas from a tube, and found that now the cathode rays did bend in an electric field after all.
Thomson concluded from these two experiments, "I can see no escape from the conclusion that [cathode rays] are charges of negative electricity carried by particles of matter." But, he continued, "What are these particles? are they atoms, or molecules, or matter in a still finer state of subdivision?"
Thomson's third experiment sought to determine the basic properties of the particles. Although he couldn't measure directly the mass or the electric charge of such a particle, he could measure how much the rays were bent by a magnetic field, and how much energy they carried. From this data he could calculate the ratio of the mass of a particle to its electric charge (m/e). He collected data using a variety of tubes and using different gases.
Thomson presented three hypotheses about cathode rays based on his 1897 experiments:
1. Cathode rays are charged particles (which he called "corpuscles").
2. These corpuscles are constituents of the atom.
3. These corpuscles are the only constituents of the atom.
The word "electron," coined by G. Johnstone Stoney in 1891, had been used to denote the unit of charge found in experiments that passed electric current through chemicals. In this sense the term was used by Joseph Larmor, J.J. Thomson's Cambridge classmate. Larmor devised a theory of the electron that described it as a structure in the ether (the invisible elastic fluid that was proposed as a substrate for light and other electrical phenomena). But Larmor's theory did not describe the electron as a part of the atom. When the Irish physicist George Francis FitzGerald suggested in 1897 that Thomson's corpuscles were really "free electrons," he was actually disagreeing with Thomson's hypotheses. FitzGerald had in mind the kind of "electron" described by Larmor's theory.
Gradually scientists accepted Thomson's first and second hypotheses, although with some subtle changes in their meaning. Experiments by Thomson, Lenard, and others through the crucial year of 1897 were not enough to settle the uncertainties. Real understanding required many more experiments over later years.
Theories about the atom proliferated in the wake of Thomson's 1897 work. If Thomson had found the single building block of all atoms, how could atoms be built up out of these corpuscles? Thomson proposed a model, sometimes called the "plum pudding" or "raisin cake" model, in which thousands of tiny, negatively charged corpuscles swarm inside a sort of cloud of massless positive charge. This theory was struck down by Thomson's own former student, Ernest Rutherford. Using a different kind of particle beam, Rutherford found evidence that the atom has a small core, a nucleus. Rutherford suggested that the atom might resemble a tiny solar system, with a massive, positively charged center circled by only a few electrons. Later this nucleus was found to be built of new kinds of particles (protons and neutrons), much heavier than electrons.
The electron itself has turned out to be not quite the creature that J.J. Thomson thought it was. According to the quantum theory developed by Albert Einstein and others, it is a mistake to think that electrons must be either particles or waves but not both. Under some conditions electrons act like particles; under other conditions they act like waves. (The wave character of electrons was in fact experimentally indicated by J.J. Thomson's own son, G.P. Thomson, who as a result shared the Nobel Prize in 1937.) Physicists have also found that electrons are only the most common members of a whole "family" of related fundamental particles -- all of them infinitesimal points carrying charge, mass, and something called "spin." Why the particles have these properties remains a mystery, a grand challenge for the next century of research.
Symposium Summary
Goals
Approximately 70 engineers and scientists will gather to assess the current state of knowledge
and to provide discussion of issues and key questions. Our goals are to achieve lively discussion
directed toward reaching consensus on (1) issues that can be resolved, and (2) issues that cannot.
Subjects
The following subjects are central to our discussions:
1. Engineering results and how they can contribute to the risk assessment process;
2. Environmental electric and magnetic fields (with an emphasis on the latter);
3. Fields in the frequency range 3 Hz to 3000 Hz, with an emphasis on power frequencies
(transients are not explicitly addressed, but may come up during discussion);
4. Engineering considerations and results in the following areas:
· field parameters · occupational/non-residential exposures
· personal exposure (PE) characterization
· field calculations
· instrumentation/measurements · general public exposures
· EMF exposure modeling · source characterization
· exposure systems · field management
· surrogates for EMF exposures · environment characterization
· quality assurance · policy issues.
In the interests of efficient focus and time management, we will not be focusing on related topics
that are beyond the scope of this symposium. These topics include the following:
· biological or health effects,
· biological mechanisms (except as they pertain to exposure metrics),
· epidemiological outcomes,
· high-frequency fields, or
· the definition of safe field levels
CALCULATIONS OF ELF ELECTRIC AND MAGNETIC FIELDS IN AIR
I. CHARACTERISTICS OF ELF FIELDS
The frequency of the power system is small enough that the electric and magnetic fields in air can be considered as if they were independent [1]. Further, the distribution of each field can be calculated under the assumption that static theory applies. Given this, both the electric and magnetic fields can be calculated from a scalar potential. With a knowledge of the conductors that make up the geometry and the distribution of surface potential and electric currents, the investigator can then calculate the electric and magnetic fields. Consider next the differences in characteristics of the electric- and magnetic-field calculation problems.
Electric Field
Usually, the potential on all power system conductor surfaces is reasonably well known. Given
this, the electric field can be calculated in a straightforward manner, using either one of two
methods:
a) by direct solution of Laplace’s equation for the potential and applying the gradient to obtain the
electric field, or
b) by finding the electric charge and then calculating the electric field by superposition of the known electric fields from elementary distributions of charge.
The electric field at any point near the power system varies periodically at the power frequency.
The rms value of this field is approximately constant in time because the voltages associated with the power system are approximately constant in time. Thus, it is possible to define a specific
electric-field value associated with a point near the power system at all times. The introduction of any dielectric or conducting material such as an animal or human subject generally will cause large perturbations in the electric field within and near the material. These perturbations depend upon the shape, orientation and conductivity distribution of the material. [2] This has serious implications for the exposure assessment problem, because the object of exposure assessment is often to calculate the fields and/or induced currents (J = s E) within the subject.
Magnetic Field
The distribution of current on power-system conductors is generally not well known. Rather, the
currents are very dependent upon power-system configuration and operating conditions. For
example, on a given line the current can vary over a given day by a factor of more than four. Significant seasonal variation is also observed. These variations occur because of more or less predictable shifts in the demand for electric power, due to daily lifestyle patterns and seasonal weather changes. Another source of power-line current and magneticfield variation is current unbalance that results in net currents.
For specified currents, however, the calculation of magnetic field can be done using superposition and a straightforward application of the Biot-Savart law. This law relates elementary distributions of currents to simple magnetic-field distributions. The difficulty of magnetic-field calculation is in relating the fields from specified currents to the real-time varying currents.
The introduction of any dielectric or conducting material such as an animal or human subject
generally will not cause large perturbations in the magnetic field within and near the material. This
dramatically simplifies the exposure assessment problem, because the object of exposure assessment is often to calculate the fields within the subject.
Magnetic materials, on the other hand, can cause perturbations in the magnetic fields. Fortunately, most subjects of exposure assessment are nonmagnetic. Note, however, that the electric fields and/or induced currents generated by the timevarying magnetic fields depend upon the shape, orientation, and conductivity distribution of the subject.
II. POWER-SYSTEM FIELD
CALCULATIONS
To illustrate how calculations can be done, consider one simple example for electric- and magnetic-field calculations. The example will be for an infinitely long single-conductor line.
Electric Fields
The electric field will be calculated here using method b) from Section I. For electric-field calculations, the earth can be assumed to be a perfect conductor and simple image theory used.
Given this, the scalar potential and electric field for y > 0 can be written in terms of the (as yet)
unknown charge per unit length. A similar procedure can be used to calculate the electric fields near three-dimensional structures with known potentials. The major difference is that finding the charge distribution is not as easy as the method shown above; it requires solution of a differential or integral equation. Recent work in this area is reviewed by Takuma and Kawamoto [3].
There are many situations (e.g., in substations, near electrical equipment and in residences) for which calculations are too complex to be practical. In these cases, systematic measurements may be preferred.
Magnetic Fields
Using the Biot-Savart law, the transverse magnetic fields of the single conductor at (x,y) = (0,h)
carrying current I1 Here, the earth has been assumed to be transparent to magnetic fields. This is reasonable at powersystem frequencies, because the earth is generally non-magnetic.
A similar procedure can be used to calculate the magnetic fields near three-dimensional structures with known currents. In this case, the procedure is not complicated by the need to calculate an intermediate unknown such as charge. Determination of the currents, however, may be difficult, especially if currents on unintentional conductors such as water pipes are important, as in the case of residences. A review of the problems of calculating magnetic fields near power systems is given in [4,5].
As mentioned in section I, the magnetic fields of a power system may vary considerably during the day and year; as a consequence, this field must be defined statistically. One reason why one must be careful with the definition of magnetic-field levels is that attempts to regulate magnetic fields are complicated by the question of how to define the magnetic field, at a point near a power line, by a single number [6].
(End part 1)III. SHIELDING
Electric Fields
Electric-field shielding is relatively easy to accomplish. Most conducting materials act as good
electric-field shields at low frequencies. For example, a wood house will provide significant shielding from an external electric field. A good survey of work in this area is given in [5].
Magnetic Fields
Low-frequency magnetic fields are usually much more difficult to shield than electric fields. Rather
than consider specific shields, a short discussion of several important parameters used to characterize the degree of shielding will be given. Good reviews can be found in [6,7]. The purpose here is to gain insight into the shielding process. The parameters of interest are discussed below.
Topology (Open vs. Closed Shields)
Shield topology is an important issue to be considered. "Closed" topologies are defined as shield geometries that completely divide space into "source" and "shielded" regions. "Open" topologies
are defined as shield geometries that do not. For closed topologies, the only mechanism by which magnetic fields appear in the shielded region is “penetration” through the shield. For open topologies “leakage” may also occur through seams or holes, or around the edges of the shield.
Material Type
It is possible to identify different shielding mechanisms with different material types. For example, when the magnetic properties (i.e., permeability) of a material dominate, shielding is by a mechanism called “flux shunting.” In this case, the magnetic flux from a source is diverted into the
magnetic material and away from the region to be shielded. When the conducting properties (i.e.,
conductivity) of a material dominate, shielding is by a mechanism known as “eddy current cancellation.” In this case, currents are induced in the conductor by the magnetic fields of the source. These currents in turn cause magnetic fields that partially cancel those of the source.
Extent and Thickness of Shield
It is obvious that the extent of a shield can be an important factor when considering “open” shields. Generally, the more the shield geometry is like a closed topology, the better the shielding. However, if penetration exceeds leakage, increasing the extent of the shield may have little effect on the shielding. The extent of a shield is also an important factor for “closed” shields. For example, it has been found that eddy-current cancellation works better for larger-diameter cylindrical or spherical shields, while flux-shunting works better for smallerdiameter cylindrical or spherical shields If penetration is the dominant mechanism, a thicker shield will usually result in greater shielding. Even in this case, however, there will eventually be diminishing returns. This is due to the skin effect.
Frequency
No eddy currents are induced in a shield at zero frequency. Thus for frequencies low enough to
ignore eddy currents, the flux-shunting mechanism dominates. Only shields with non-unity relative permeability will be effective in this case. As the frequency increases, eddy-current induction becomes more important. Thus, “eddy current” shielding will generally be greater at higher frequencies.
Location and Orientation of Sources
The effectiveness of shields is known to be very dependent upon source location and orientation.
Gaps and Apertures
A shield is often constructed of several pieces. It can be shown that the electrical and/or magnetic
continuity of the shield at junctions may have a significant impact on the effectiveness of the overall shield. The size of the gap need not be large for this to be the case. Further, wire connections at periodic locations along the shield may not be sufficient. Apertures cut in a shield may also influence shield performance. This will definitely be true if the aperture in the shield is oriented to cut the natural path of either magnetic flux or electric current in the shield.
ftp://ftp.emf-data.org/../pub/emf-data/ ... yn-06a.pdfIV. IMPLICATIONS FOR RISK ASSESSMENT
Electric Field
· The unperturbed electric-field calculations are quite accurate if the geometry and voltages of the sources are known.
· In complex geometries, calculations are difficult and measurements may be preferable.
· The rms value of the unperturbed electric field varies from point to point in space but not much with time.
· The electric field inside a subject due to the unperturbed electric field is dependent upon the subjects’ shape, orientation, conductivity distribution, and proximity to other objects.
Magnetic Field
· For a given current and source geometry, calculations of unperturbed magnetic fields are quite accurate.
· Determination of currents can be difficult, especially if currents on unintentional conductors such as water pipes are important.
· The unperturbed magnetic field varies from point to point in space and with time because source currents generally vary with time. Thus, statistical calculations of magnetic fields are recommended.
· The magnetic field within a subject is usually approximately equal to the unperturbed magnetic field.
· The electric field inside a subject due to the time-varying unperturbed magnetic field is dependent upon the subject’s shape, orientation, and conductivity distribution.
V. REMAINING QUESTIONS
1. Which field is important? Is it the electric field, the magnetic field, or the current density?
2. Which aspect of the field is most important? Is it the peak value, the time-weighted average,
the frequency content, the polarization, or something else?
3. For electric-field exposure calculations, can the effect of the subject’s changing orientation and
local environment be quantified?
4. There is not enough experience with the calculation of currents on complex systems of conductors. Is it realistic to do these calculations, or should measurements be relied on?
5. It is known that net currents can be an important parameter for calculation of magnetic fields. Can situations for which these are important be identified?
6. How can the statistics used to describe time variation of currents be used in calculations of magnetic field statistics?
7. Magnetic-field shielding is known to be highly dependent upon source characteristics. In many
cases, it is not easy to determine the sources. For these cases, can an easier way be found so that accurate shielding calculations can be done? If not, are there shielding schemes that are less dependent upon source geometry?
ftp://ftp.emf-data.org/../pub/emf-data/ ... yn-06b.pdfField-induction Effects
It is well known that alternating electric (E) and magnetic fields (B) outside the body are capable
of inducing electric fields within the body. While this induced E-field is the exposure metric most closely related to tissue stimulation, the density of current flowing in tissues (J) expressed in
mA/m is also sometimes used. This parameter is proportional t 2 o the induced E-field by Ohm's Law, J =x E, where x is the tissue conductivity.
A variety of biological responses ranging from weak sensory effects to cardiac fibrillation has been observed at induced current densities greater than 10 mA/m2, with the severity of the effects directly related to the magnitude of the field. Of all the mechanisms proposed to "explain"
biological responses to electric and magnetic fields, only field-induction mechanisms are supported by a coherent body of theoretical and biological evidence.
ftp://ftp.emf-data.org/../pub/emf-data/ ... syn-13.pdfI. INTRODUCTION
Field management minimizes the impact that magnetic or electric fields have on their surroundings. It may be necessary to reduce electric- or magnetic-field interference or to allay public or employee concern.
The management of magnetic or electric fields may involve the following:
· educational and measurement programs
· prudent avoidance
· site arrangement
· design change
· cancellation
· shielding
or a combination of these methods.
A variety of field-management techniques has been developed so that they are available for use should they be needed to reduce fields [1,2,3,4,5,6,7,8,9].
Management of electric fields, when required, is usually accomplished through material shielding or source rearrangement. Examples of electric-field shielding techniques are conductive suits used by transmission live-line workers and conductor rearrangement or compaction of power lines. Power-line phase arrangement or compaction can be used to reduce electric fields, although corona effects such as audible noise, radio noise, and corona loss may increase. Grids
of wires, grounded metal-covered walkways, or appropriately placed trees may also be used to reduce electric fields and associated electric shocks that may be due to the electric fields. Electric-field shielding techniques are discussed in Reference 9. Management of magnetic fields can be more difficult because they are not effectively shielded by many materials. This synopsis will focus on magnetic-field management.
II. MAGNETIC FIELD-MANAGEMENT
TECHNOLOGY
Figure 1 provides insight to several field-management strategies. It provides the magnetic-field equations for four different wire configurations. The first is a single current-carrying wire. The second is an example of lines carrying equal but opposite currents, such as the wiring in a residence. The third example has the current in one of the conductors split and positioned on either side of the other conductor. The fourth wiring example is a current loop similar to the current flow that might be found in many common appliances.
Five methods of field management can be derived from
observation of Figure 1.
· Increase distance (R) from the conductors.
· Match the current (I) in a conductor with an opposing current in a nearby conductor.
· Decrease the distance (P) between the conductors or the area (A) of the loop.
· Split the current (I) of one conductor and position around the other conductor.
· Decrease the current (I).
A sixth field-management option is to reduce the field in selected areas (shielding) by use of conducting materials that cancel the field through induced eddy currents, or by flux-shunting materials that redirect the magnetic field. Essentially all field-management strategies make use of one or more of these techniques.
It reminds me of an old magazine I read when I was a little younger. It was related to this question in a way but then pertaining to photons. It tried to show it by asking how one and the same object can fit in a triangle but also can fit a circle.junglelord wrote:If it is not a particle and not a wave, but can present as either, then it must be neither.
http://www.patent-invent.com/electricit ... ctron.htmlThe electron is a subatomic particle. In an atom the electrons surround the nucleus of protons and neutrons in an electron configuration. The word electron was coined in 1894 and is derived from the term electric, whose ultimate origin is the Greek word 'ηλεκτρον, meaning amber. Electrostatic charge can be generated by rubbing the amber with the pelt of an animal e.g. a cat and has been done so while analysing elementary charge for the first time. The ending -on, shared by most subatomic particles, was used in analogy to the word ion.
As stated above, electrons have an electrical charge. When they move, they generate an electric current. Because the electrons of an atom determine the way in which it interacts with other atoms, they confer chemical properties to elements and therefore play a fundamental part in chemistry.
The term electron usually refers to negatrons with a negative electric charge of −1.6 × 10−19 coulombs, and a mass of about 9.11 × 10−31 kg (0.51 MeV), which is approximately 1⁄1836 of the mass of the proton. These are commonly represented as e−. Sometimes the term is used, as proposed by Carl D. Anderson, to refer to both negatrons and positrons. Positrons have the same mass and an electric charge of the equal but positive value.
The motion of the electron about the nucleus is a somewhat controversial topic. The electron does not exhibit motion in the physical sense — it does not "float"; rather, it seems to appear in and out of existence, at various points around the nucleus (of course, 90% of the time the electron can be found in its designated orbital). A simple analogy would be a firefly, in a dark room, lighting up at various points about a central light source — it can light up anywhere, but it is most likely to appear closer to the source than otherwise. At present, we cannot predict both the momentum and position of an electron. This is a limitation described by the Heisenberg uncertainty principle, which, simplified and tailored for quantum particles, simply states that the more accurately we know a particle's position, the less accurately we can know its momentum and vice versa.
So-called "static electricity" is not a flow of electrons. More correctly called a "static charge", it refers to a body that has more or fewer electrons than are required to balance the positive charge of the nuclei. When there is an excess of electrons, the object is said to be "negatively charged". When there are fewer electrons than protons, the object is said to be "positively charged". When the number of electrons and the number of protons are equal, the object is said to be electrically "neutral". Electrons and positrons can annihilate each other and produce a photon. Conversely, a high-energy photon can be transformed into an electron and a positron by a process called pair production.
In quantum mechanics, the electron is described by the Dirac Equation. In the Standard Model of particle physics, it forms a doublet in SU(2) with the electron neutrino, as they interact through the weak interaction. The electron has two more massive partners, with the same charge but different masses: the muon and the tauon.
The antimatter counterpart of the electron is its antiparticle, the positron. The positron has the same amount of electrical charge as the electron, except that the charge is positive. It has the same mass and spin as the electron. When an electron and a positron meet, they may annihilate each other, giving rise to two gamma-ray photons, each having an energy of 0.511 MeV (511 keV). See also Electron-positron annihilation.
Electrons are also a key element in electromagnetism, an approximate theory that is adequate for macroscopic systems.
The periodic law states that the chemical properties of elements largely repeat themselves periodically and is the foundation of the periodic table of elements. The law itself was initially explained by the atomic mass of the elements. However, as there were anomalies in the periodic table, efforts were made to find a better explanation for it. In 1913, Henry Moseley introduced the concept of the atomic number and explained the periodic law with the number of protons each element has. In the same year, Niels Bohr showed that electrons are the actual foundation of the table. In 1916, Gilbert Newton Lewis and Irving Langmuir explained the chemical bonding of elements by electronic interactions.
http://www.chemguide.co.uk/basicorg/bon ... itals.htmlELECTRONIC STRUCTURE AND ATOMIC ORBITALS
Atomic orbitals
Orbits and orbitals sound similar, but they have quite different meanings. It is essential that you understand the difference between them.
The impossibility of drawing orbits for electrons
To plot a path for something you need to know exactly where the object is and be able to work out exactly where it's going to be an instant later. You can't do this for electrons.
Suppose you had a single hydrogen atom and at a particular instant plotted the position of the one electron. Soon afterwards, you do the same thing, and find that it is in a new position. You have no idea how it got from the first place to the second.
You keep on doing this over and over again, and gradually build up a sort of 3D map of the places that the electron is likely to be found.
In the hydrogen case, the electron can be found anywhere within a spherical space surrounding the nucleus. The diagram shows a cross-section through this spherical space.
95% of the time (or any other percentage you choose), the electron will be found within a fairly easily defined region of space quite close to the nucleus. Such a region of space is called an orbital. You can think of an orbital as being the region of space in which the electron lives.
What is the electron doing in the orbital? We don't know, we can't know, and so we just ignore the problem! All you can say is that if an electron is in a particular orbital it will have a particular definable energy.
http://www.chemistry.mcmaster.ca/faculty/bader/aim/Atoms and Molecules
An Introduction to the Electronic Structure of Atoms and Molecules
The beginning student of chemistry must have a knowledge of the theory which forms the basis for our understanding of chemistry and he must acquire this knowledge before he has the mathematical background required for a rigorous course of study in quantum mechanics. The present approach is designed to meet this need by stressing the physical or observable aspects of the theory through an extensive use of the electronic charge density.
The manner in which the negative charge of an atom or a molecule is arranged in three-dimensional space is determined by the electronic charge density distribution. Thus, it determines directly the sizes and shapes of molecules, their electrical moments and, indeed, all of their chemical and physical properties.
Since the charge density describes the distribution of negative charge in real space, it is a physically measurable quantity. Consequently, when used as a basis for the discussion of chemistry, the charge density allows for a direct physical picture and interpretation.
This web page begins with a discussion of the need for a new mechanics to describe the events at the atomic level. This is illustrated through a discussion of experiments with electrons and light, which are found to be inexplicable in terms of the mechanics of Newton. The basic concepts of the quantum description of a bound electron, such as quantization, degeneracy and its probabilistic aspect, are introduced by contrasting the quantum and classical results for similar one-dimensional systems. The atomic orbital description of the many-electron atom and the Pauli exclusion principle are considered in some detail, and the experimental consequences of their predictions regarding the energy, angular momentum and magnetic properties of atoms are illustrated. The alternative interpretation of the probability distribution (for a stationary state of an atom) as a representation of a static distribution of electronic charge in real space is stressed, in preparation for the discussion of the chemical bond.
Chemical binding is discussed in terms of the molecular charge distribution and the forces which it exerts on the nuclei, an approach which may be rigorously presented using electrostatic concepts. The discussion is enhanced through the extensive use of diagrams to illustrate both the molecular charge distributions and the changes in the atomic charge distributions accompanying the formation of a chemical bond.
http://www.wolfram-stanek.de/maxwell/index.htmlThese websites shall provide an INTRODUCTION into the interdisciplinary possibilities
of Maxwell's equations, using mnemonics and the wide field of technical applications.
A further focus is concentrated on different transformation equations
and several additional fields caused by moved objects.
Finally influences from both special relativity and quantum mechanics are combined in one equation.
http://physics.nmt.edu/~dynamo/articles.htmlThe New Mexico Liquid Sodium α ω Dynamo Experiment:
The Mechanism of Our Magnetic Universe
We expect to demonstrate with a laboratory experiment the primary mechanism by which magnetic fields are generated in the universe.
Dynamos and Electric Generators
Every electric motor is an electric generator and every electric generator is an electric motor. It just depends upon whether electric energy is converted to mechanical or mechanical energy is converted to electrical, or which is driver and which is driven.
In German "dynamo" is synonymous with electric generator, but in English, "dynamo" is archaic for all but astrophysical electric generators. The dynamo was invented in Germany by Siemans, 18??. This dynamo as well as all electric motors/generators depend upon insulated wire where the topology of the current can be altered or arranged to make any direction or topology of magnetic field desired.
The problem in astrophysical bodies is how can a simple sphere of conducting fluid, a star, (or an accretion disk forming a black hole) manage to create the complicated topology of currents or fields necessary to create a dynamo? The answer lies in the surprising coherence of the fluid flows created by convection in a rotating, stratified fluid, i.e., a star or accretion disk: See The α ω Dynamo and The Pulsed Jet Rotation Experiment. The New Mexico Liquid Sodium α ω Dynamo Experiment was designed to demonstrate just this naturally occurring coherence that leads to such a dynamo.
The range in size of natural and man-made dynamos or electric generator- motors is awesome, 46 orders of magnitude, from the smallest (common) motor, and electric watch, to the awesome galactic black hole accretion disk dynamo.
Astrophysical Background
Stirling A. Colgate and Hui Li, T-6, Los Alamos National Lab
1. Evidence for Immense Magnetic Field Energy and Flux
Radio astronomy aperture synthesis pictures of quasars or active galactic nuclei (AGN) within the special environment of clusters of galaxies reveal massive regions of coherent magnetic flux: Fig. 1, 3C465, 3C75, (Eilek and Owen, 1999) and Fig. 2, Hydra, (Taylor and Perley, 1993). This magnetic field is inferred using the technique of measuring the Faraday rotation by a foreground screen of the vector of polarized emission of an underlying, highly polarized source. In order for this effect to be observed, this screen must have: (1) a highly polarized source, (2) with small internal Rm, (3) lying behind, (4) a region of highly ordered Rm, (5) without significant emission, and (6) further requiring both a highly ordered field and (7) a uniform electron density. A modification of any one of these seven conditions rapidly averages a potentially large Rm to a negligible value. The fact that the field can be measured and is so strong, highly oriented, and uniform and furthermore that the electron density is equally as uniform over dimensions of 100 kpc or 10 times the size of our galaxy is truly extraordinary. The energy derived from the size and therefore volume of coherent field is ~ 1059 to 1060 erg. This energy is so large, a million times that of the field energy of our own galaxy and orders of magnitude larger than the binding energy of typical galaxies, that an extraordinary source of this energy is necessary (Colgate and Li, 1999). The underlying highly polarized source is an AGN. This implies that the AGN is the source of this immense magnetic energy. A massive black hole, ~ 108 Mʘ is presumed to power every AGN from the black hole binding energy, ~ 1062 erg. A significant fraction of this energy is therefore required to create the fields inferred from Faraday measurements. Furthermore an even larger magnetic energy, ~ 1060 to 1061 erg is required to explain the underlying polarized synchrotron source, which is also the giant radio lobes of typical, average field AGN, (not in clusters). One calculates this still larger energy by assuming that the radio emission from the giant radio lobes is synchrotron radiation.
This emission requires both a magnetic field and highly energetic electrons. The minimum energy is determined from the minimum sum of the accelerated electrons (plus ions) and magnetic field strength necessary to emit the observed synchrotron radiation. This minimum occurs when the two energies are equal. If the energy in energetic electrons is just a small fraction, ~ 1%, of the ion energy as expected from our galactic cosmic ray spectrum, then the total energy is an order of magnitude larger. The Faraday rotation measures indicate that strong magnetic fields of immense energy are associated with AGN. This substantiates the synchrotron radiation interpretation of still larger energies implied for most sources. Finally, comparable field energies are seen in the cluster as a whole (Clarke,Krönberg, & Böhringer 2000).
http://home.slac.stanford.edu/pressrele ... 070511.htmScientists have long suspected that carbon belongs on the short list of materials that can be magnetic at room temperature, but proof of that hypothesis has languished in controversy for nearly a decade. Since antiquity, magnetism has appeared to be a trick performed only by iron, nickel, cobalt and a handful of rare alloys.
Carbon's possible magnetic identity first emerged when meteorites were found containing bits of the magnetized element, but those flecks of carbon were packed in close proximity to nickel, leading to the suspicion that the observed magnetism came from the nickel. But until now, attempts to prove that pure carbon can be magnetized have remained unconvincing.
According to Ohldag, magnetism is an "ordering phenomenon." All atoms behave like tiny magnets because of the spin orientation of electrons, he says. When enough of those tiny magnetic spins, or "moments," align, the material emanates a measurable magnetic field. The electron spins of iron align readily, even at high temperatures, making it an ideal magnetic material.
Carbon's electrons are arranged in such a way that magnetization has, until recently, seemed theoretically impossible. Carbon-containing meteorites found in 1999 challenged that notion, and subsequent research showed that transient magnetism on a small scale can be temporarily induced in carbon when it is brought near other magnetized elements.
Ohldag, in collaboration with six researchers from Lawrence Berkeley Lab's Advanced Light Source (ALS) and the Institute for Experimental Physics in Leipzig, Germany, have now shown that pure samples of carbon can be made permanently magnetic at room temperature. In Leipzig, Ohldag's team applied a beam of protons to disrupt and align a portion of the electrons in samples of pure carbon, magnetizing tiny, measurable spots within the carbon.
A carbon film is hit by a high-energy proton beam, causing the magnetic moments of the atoms to align around the beam impact area and creating a ring-shaped magnetic pattern that can be imaged with a magnetic-force microscope. The X-ray microscope can also be tuned to "scan" the sample for magnetism associated with other elements. The absence of a ring pattern in scans for cobalt, nickel and iron prove that the sample contains only carbon.
http://en.wikipedia.org/wiki/FullereneSo-called endohedral fullerenes have ions or small molecules incorporated inside the cage atoms. Fullerene is an unusual reactant in many organic reactions such as the Bingel reaction discovered in 1993. The first nanotubes were obtained in 1991.[2]
Minute quantities of the fullerenes, in the form of C60, C70, C76, and C84 molecules, are produced in nature, hidden in soot and formed by lightning discharges in the atmosphere
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