Forces between electric charges in motion. Magnetic Effects Forces between electric charges in motion.

Familiar Ideas. An phenomenon apparently unrelated to electricity is magnetism. The interaction of compasses with the earth's magnetic field. Fridge magnets or magnets on children's toys.

Magnetic forces. There are two types of magnetic poles, conventionally called North and South. Like poles repel, and opposite poles attract.

Magnetism differs from electricity. Unlike electric charges, magnetic poles always occur in North-South pairs. There are no magnetic monopoles.

Weber's Theory Considers the molecular alignment of the material. All magnetic substances are composed of tiny molecular magnets. Unmagnetized material has the magnetic forces of its molecular magnets neutralized by adjacent molecular magnets. Eliminating any magnetic effect.

A magnetized material. Most of its molecular magnets lined up. Molecules thus aligned will then have one effective north pole, and one effective south pole.

Domain Theory. Based on the electron spin principle. Atoms contain one or more orbital electrons. Electrons have angular momentum (spin). An electron has a magnetic field about it along with an electric field. The effectiveness of the magnetic field of an atom is determined by the number of electrons spinning in each direction.

Electron Spin If equal numbers of electrons spin in opposite directions, the atom has no magnetic qualities. If more electrons spin in one direction than another, the atom is magnetized. http://www.tpub.com/neets/book1/chapter1/1h.htm

Domain Accumulation. If a material is subjected to an external magnetic field, the domains will align. More and more domains join the domain as the internal field strengthens.

Magnetic Properties of Solids Diamagnetism. Paramagnetism. Ferromagnetism. http://hyperphysics.phy-astr.gsu.edu/Hbase/solids/magpr.html

Diamagnetism. Diamagnetism is a property of all materials, which opposes applied magnetic fields, but is very weak. Orbital motion of electrons creates tiny atomic current loops, which produce magnetic fields. When an external magnetic field is applied to a material, these current loops will tend to align in such a way as to oppose the applied field.

Paramagnetism. Materials exhibit a magnetization which is proportional to the applied magnetic field in which the material is placed. In most materials the magnetic moments of the electrons cancel, but in materials which are classified as paramagnetic, the cancellation is incomplete.

Ferromagnetism. Iron, nickel, cobalt and some of the rare earth elements. Exhibit a long range ordering phenomenon at the atomic level. Causes the unpaired electron spins to line up parallel with each other in a region called a domain. A small externally imposed magnetic field can cause the magnetic domains to line up with each other and the material is said to be magnetized.

Permanent Magnetism Ferromagnets will tend to stay magnetized. This tendency to "remember their magnetic history" is called hysteresis. The temperature where the ferromagnetic property disappears as a result of thermal agitation. This temperature is called the Curie temperature.

Magnetic Fields The space surrounding a magnet where magnetic forces act. All magnetic fields have two poles (N and S).

Opposite Poles Attract.

Like Poles Repel

Magnetic Field Breaking a magnet in half does not separate the poles but produces two magnets with two "poles" each. The "north" and "south" poles of a magnet or a magnetic dipole are labeled similar to north and south poles of a compass needle. This magnetic field continues inside of magnet (so there are no actual "poles" anywhere inside or outside of a magnet).

The Earth's Magnetic Field. http://csep10.phys.utk.edu/astr161/lect/earth/magnetic.html

Origin of the Magnetic Field The origin of the Earth's magnetic field is not completely understood. Electrical currents produced by the coupling of convective effects and rotation in the spinning liquid metallic outer core of iron and nickel. This mechanism is termed the dynamo effect. http://csep10.phys.utk.edu/astr161/lect/earth/magnetic.html

The Magnetosphere http://csep10.phys.utk.edu/astr161/lect/earth/magnetic.html

The Nature of the Magnetosphere Two factors determine the structure and behavior of the magnetosphere: The internal field of the Earth (its "main field") appears to be generated in the Earth's core by a dynamo process. The solar wind is a fast outflow of hot plasma from the sun in all directions which distorts the symmetry of the magnetic field of the Earth in space. http://en.wikipedia.org/wiki/Magnetosphere

Radiation Belts. The "inner radiation belt" of protons with energies in the range 10-100 MeV (million electron volts), called the Van Allen belt. It is centered on field lines crossing the equator about 1.5 RE from the Earth's center. A population of trapped ions and electrons was observed on field lines crossing the equator at 2.5-8 RE. The high-energy part of that population (about 1 MeV) became known as the "outer radiation belt“. http://en.wikipedia.org/wiki/Magnetosphere#General_properties

Magnetospheric Protection The magnetosphere deflects radiation and solar wind particles. Coronal Mass Ejections (CME) can compress the magnetosphere and expose satellites and parts of the earth to radiation and energetic particles from the sun. CME events are sometimes called solar storms.

Solar Storms (space weather) Space weather refers to violent transfers of matter and energy from the sun to the Earth. $4 billion in satellite losses can be traced to space weather damage. The last major space storm caused an electrical blackout in Quebec. Solar flares have cost the airline industry millions of dollars. http://www.solarstorms.org/

Satellite Losses Solar Panel Degradation. Energetic particles from the sun, produce physical damage to silicon-based solar cells. Premature Atmospheric Reentry. Solar storms heat the upper atmosphere causing increased drag which accelerates orbit decay. Sudden Event Upsets. High-energy particles such as cosmic rays or protons from solar flares, do considerable internal damage to spacecraft.

Electrical Blackouts Space weather disturbances cause Geomagnetically Induced Currents , these GICs can enter a transformer through its Earth ground connection. The added DC current to the transformer causes the relationship between the AC voltage and current to change. One hundred amperes of GIC current or less will cause a transformer to overload. Space weather events can damage equipment over wide geographic regions.

Losses to the Airlines Most airlines use polar routes for intercontinental flights to save time and fuel. During a solar flare, radiation levels at the poles increase significantly. Airlines route flights at lower altitudes at a much greater cost in fuel (3,000 extra gallons at a cost of over $10K).