Magnetics

Chapter 10

Magnetics

Magnetic Field of a Permanent Magnet

Iron filings arrange themselves along the lines of a magnetic force, making the lines visible. Magnets are surrounded by a magnetic field, and the magnetic lines of force run from one pole of the magnet to the other.

Orion Press Photo Library

Microsoft ® Encarta ® 2006. © 1993-2005 Microsoft Corporation. All rights reserved.

Magnetic field strength 20T, B:10^-15 to 50T (10^-11 to 500kg)

Lorentz force F=-e(E+v x B)

High magnetic field >50T duration of 10^-5s

Flux density = 100T (1MG)

Magnetic pressure 4 x 10¹⁰ PA

Electric field strength E:<5 x 10⁸ Vm^-1

Each electron with a charge 1.6 x 10^-19 c, circles the atom once in 10^-16 s, if we divided the electronic charge by this time interval. We see the orbiting electron is equivalent to a current of 1.6 x 10^-3 A. Such a current produces a magnetic field on the order of 20T at the center of the circular path. Magnetic field lines always form closed loops, they don’t begin or end any where.

A varying magnetic field induces an EMF and hence an electric field. “Faraday’s law” The charge required to deposit or liberate a mass=m, F=Faraday’s constant, z= charge of ion, M=relative ionic mass. Magnetic fields are generated by moving charges “Ampere’s Law.” Where dB is the infinitesimal element of the magnitude of the magnetic flux density, at the distance r at point p from the element length dl of a conductor, the magnetic permeability of free space, 1 is the current flowing through the conductor and the angle between the direction of he current and the line joining the element of the conductor and P. Electromagnetic waves carry energy as they travel through space with an average power per unit area is where Em and Bm are the max values of the electric and magnetic fields. Electromagnetic waves transport momentum as well as energy. The speed of light, the frequency f and wave are related by c=fλ. The ratio of the electric field to the magnetic field in an electromagnetic wave equals the speed of light. Electromagnetic waves flow forward and backwards in time. Mutual induction uses oscillating magnetic fields.

Gauss’ Law the total electric flux normal to a closed surface in an electric field is proportional to the algebraic sum of the electric charges within the surface. Cooperative phenomenon – phase transition. Maxwell’s theory showed that magnetism and electricity are one and the same. Force and light itself is a manifestation of the electromagnetic force. Maxwell realized that if the charging electric field could produce a changing magnetic field and the changing magnetic field could produce a changing electric field, the two components of the single unified electromagnetic field could get along quite nicely together without any need for electric currents or magnetic’s at all. The equations say that a self-reinforcing electromagnetic field with the electricity producing the magnetism and the magnetism producing the electricity could set off through space on its own once it was given a push to start.

Isothermal renanence

Ti = poor titanomagnetities Ti = poor ilmenohaematites. The two commonest magnetic minerals in most terrestrial rocks. They form solid solutions at temperatures above 900 degrees c but have a rhombohedral structure. Silica rich rocks (acidic) have compositions approaching that of the ilmenohaematite series. Ultra basic rocks (silica poor) titanomagnetite. Quench-cooling is fairly rare under most geological conditions. More normal cooling rates result in the high temperature solid solutions resolving to form intergrowths between titanomagnetite (cubic) series and ilmenohaematite (rhombohedral).

Shape anisotropy, the magnetic field within a magnetic grain is uniform, the magneto static force due to the magnetic poles at the surface depend on their separation. In spherical grains the separation of the surface poles is constant in all directions, so spheres have zero shape anisotropy. Magnetic properties depending on the actual composition. The unit cell size increases with increased Ti content and Curie temperature decreasing.

Magnetic units, the force between two poles, of strength in a vacuum given the distance between them and the constant of the permeability of free space with a sI value. The magnetic field of a material and its intensity of magnetization are both measured in amperes per meter (Am^-1) and are related to the magnetic induction in a magnetized medium, which is measured in tesla (T). In a three axis system cause anhysteretic magnation rotations, because gyro magnetic magnetization which dominate the natural remanence with a tendency to become “noisy” at fields over 50mT. A three dimensional statistical analyses, distribution vector points on a sphere would have a probability density, the angular distance between an individual point and the true mean of the vector population and the precision parameter, varying from zero if all vector points are uniformly distributed, to infinity if they are all identical to the mean. In the Fisher distribution the precision, is for the absolute total population of the vector points on a sphere. K precision parameters can be estimated for the values greater than 7 and for K greater than 3. In the analyses of unit vectors of values of K greater than 10 indicate that the observed mean is close to the true mean of the total population. Uniformly magnetized spheres. Taniclination = 2 tan (latitude) the variation in total intensity according to latitude. The formula for the magnetization on the surface of a uniformly magnetized sphere with the total magnetic moment. Spherical harmonic analysis of the field show that virtually all the field (greater than 99.5%) is of a internal origin with the balance attributable to the effects of electrical currents in the upper mantle. 80% of the geomagnetic field is described in terms of the first harmonics (based on 8 internal fields). If electrical currents being maintained as a result of convective motion in the outer core, it will create a uniform magnetization in the inner (solid) core. Magnetization as a fundamental property of rotating matter is generally accepted,  the field is generally accepted that the field is generated by electrical currents circulating in the core.

Nuclear Magnetic resonance is the magnetic movement along an axis and the nuclear gyro magnetic ratio of the energy of that spin. The magnetic field is expressed in tesla (T) it is the energy level between the two states. The frequency for the transition of protons is 11.7T 500 x 10⁶ Hz and 18.1T 800 x 10⁶ Hz. Black Body radiation – the electromagnetic radiation density in an evacuated enclosure is brought to a temperature radiation is produced. The spectral distribution of the radiation energy is denoted by the angular frequency and is not dependent on material it is determined solely by temperature. On the elements surface energy is propagated with the velocity of light and all points contribute radiation. A fraction of the radiation present in the volume will restrict the wave. The isotropic radiation is suspended by the surface. The radiation incident is obtained by integrating the volume of the cone contained in the hemisphere. The total radiation incident is obtained over the complete hemisphere. The energy radiated per unit time and unit area corresponds to the total energy in the enclosure and includes the total energy for each spectral component. Since radiation and momentum differ by a factor of 1/c the momentum is transferred to the walls and is the radiation pressure. If the wall is the ideal reflector, the radiation will be reflected and the momentum is transferred. The energy emitted per second per square centimeter of the black body are  the non-degenerative energy levels of an atom, the latter reacts with the black body radiation by emitting or absorbing light quanta of a magnitude dependent on the state and the density of the spectral energy and the radiation field absorbed from the field. A 3 dimensional oscillator is 2π ²e²/m u (w).

Earth’s Geomagnetic fields

North pole is at 73⁰ N 100⁰W South pole is at 68⁰ S 143⁰ E

The total intensity which varies from 30μT near the equator to 60μT near the poles. The total magnetic moment being at present 8.01 x 10²²Am². A 80% geomagnetic field can be described in terms of first harmonics, corresponding to a single geocentric dipole inclined at 11 ½⁰ from earths arc of rotation with magnetic poles at 78.5⁰N 70⁰W and 78.5⁰S 110⁰E. This is an average tendency for the total magnetic field strength to decrease by about 18nT year^-1. This would result in a lost of the geomagnetic field in 200 years time.

The field has a distinct westward drift of a non-dipole component at 0.2⁰ year^-1. 20,000 km is the limit that distant gravitational forces disrupt planetary bodies. The possibility that universal gravitational constant G may not be constant, but could vary on a long time scale. Which could be major important in the evaluating the significance of the red shift of the light from distant galaxies.

On a parochial scale it has been suggested that many terrestrial features result from changes in the constant increases in earth’s radius is during a 1/3 during the last 200 million years. G has changed by more than ± 1% during the 4.5 billion years. The equator is where earth’s rotational surface speed is the highest, the higher the elevation the less work required. Delta – Vn is the horizontal velocity to take orbit speed at earth equator the payload would start with a Vn of 1,000 mph with 11 tons per person – life support supplies for 2 years. Orbital speeds 17,500 mph to 24,000 mph. Total atmospheric pressure 14.7 psi oxygen make up to 21% of atmospheric pressure at sea level 3.09 psi. Space suits 3.5 psi. Spacecraft 5 psi.

At 64,800 mph revolving around the sun it’s not speed that harms the body. Positive G force – head to foot, Negative G force – foot to head. 4 G positive force on 150lb = 600 pounds, 5 G is blackout.

Biological aspects of Magnetations

Corn grows faster in a magnetic field strength stronger than earths. Many animals (insects, invertebrates, bacteria) have magnetic particles in their brains or necks that appear to have an influence on their behavior. There are other similar direct effects of geomagnetic fields on animals, such as high incidence of heart attacks during magnetic storms. Micro- organisms form new species at time close to polarity transitions and other species become extinct. There is a 50:50 probability occurring at the time, The cause thought to be related to decreases in strength of the field which would cause a restriction in the height of the ionosphere and allow a greater penetration of cosmic and solar radiation. This also causing mutation rates to increase. The increase in radiation is calculated to be less than 10%, even for a total loss of the geomagnetic field. Out planet in a 24,000 year orbit passes through a photon belt of light twice, each passage lasting about 2,000 years, causing disruptions in magnetic fields.

Magnetic Levitation above a Superconductor

A small cylindrical magnet floats above a high temperature superconductor. The vapor is from boiling liquid nitrogen, which keeps the superconductor in a zero-resistance state. As the magnet is lowered toward the superconductor, it induces an electric current, which creates an opposing magnetic field in accordance with Ampere’s law. Because the superconductor has no electrical resistance, this induced current continues to flow, keeping the magnet suspended indefinitely.

Photo Researchers, Inc./David Parker/IMI/Science Source

Microsoft ® Encarta ® 2006. © 1993-2005 Microsoft Corporation. All rights reserved.

Organic Superconductors

Elliot theory

According to the model where torsional oscillations of the ET Molecule can life symmetry restrictions and enable introchain and interchain spin relaxation to cause broaden line widths, higher pressure, should stiffen the crystal lattice which should reduce the oscillations and thereby sharpen the ESR line width. An empirical formula for describing this situation has been proposed.

Fundamental interactions:

1.      Gravitational interactions are 10⁴⁰ times weaker than electromagnetic interaction.

1. A gravitational interactions are long-range atomic-negligibly weak.

2.      Weak interactions are 10¹⁰ times weaker than electromagnetic interactions.

3.      Electromagnetic interactions are the exchange of virtual photons.

4.      Strong interactions are 10² times stronger than electromagnetic interactions and are the exchange of virtual mesons.

Superconductors

The critical temperature at which electrical resistance drops to zero, subjected to magnetic field (the temperature always drop to a lower temperature in a magnetic field.) high temperatures means anything above 23K. The Meissner effects is a phenomenon relates to the ability to exclude a magnetic field – a permanent magnet will float above a superconducting material at its critical temperature (the higher the magnetic field the lower the temperature). Magnetic susceptibility is measured by the degree to which magnetic fields are distorted by the material. Evidently oxygen had to be present in the atmosphere for the creation of superconductivity when mixing and baking small amounts of material.

Super molecular machines

Supramolecular machines are organized systems of cooperating molecules, where the individual molecules constitute the functional components. Such systems have a great potential as sensors and actuators, information processing devices, memories with high storage capacity tailored catalyst for complex “chemical” reactions and energy conversion systems. The most intricate devices of the kind are living systems. Tools and machines are functional units, systems where different components interact to perform tasks that cannot be done by any component. In bio-systems, most intricate supramolecular machines – for example; machines transforming “light” energy into chemical energy by electron or proton pumping are present. The energy is by self-assembly from molecular components of complicated structures able to interlock in a distinct manner. Supramolecular engineering are involved in the programmed environment changes. The critical point is to find appropriate conclusions leading to the evaluation of a life like system at the end of a long sequence of consistent steps.

Magnetic bubble memory

This consists of materials, such as magnetic garnets, that are easily magnetized. A thin film on a non-magnetic substrate constitutes a bubble – memory chip. When a magnetic field is applied to a chip, by placing it between two permanent, garnets, cylindrical domains are formed. The bubble constitutes a magnetic region of one polarity surrounded by a magnetic region of the opposite polarity. Information is represented as the presence or absence of a bubble at a specified storage location and is retrieved by means of a rotating magnetic field. A chip measures 15mm² or 25mm² in closed in two permanent magnets and two rotating field coils; each chip can store up to 1 million bits.