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Magnetism! (Magnetic Materials (Ferromagnetic (These magnets consist of…
Magnetism!
Magnetic Materials
Diamagnetic
These atoms don't have any unpaired electrons. If they are placed near magnets, the electrons' magnetic poles will actually align against the magnetic field so that they are repelling.
Ferromagnetic
These magnets consist of bunches of magnetic domains (atoms with their poles aligned). These domains can be aligned to create permanent magnets.
The three common ferromagnetic materials are iron, cobalt, and nickel.
Paramagnetic
These atoms have unpaired electrons with their own magnetic field. These electrons can be aligned to another magnet to create a temporary magnetic material.
Magnets!
Like electrons and protons, North poles attract South poles and vice versa. North poles repel other North poles, and South poles repel other South poles.
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Electromagnetism
Magnetic fields can be created by a current, or just a moving charge, for that matter.
Moving Charge
When moving charges interact with magnetic fields, they experience a force perpendicular to their velocity and the magnetic field
This force is equal to qBv*sin(theta), where B is the strength of the field in Tesla and theta is the angle between the velocity and field line.
Electrical Current
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The force is equal to ILB where L is equal to the length of the conductor. This equation is for positive currents, so for electrons, the direction of the force needs to be reversed.
Electrical Induction
Electricity can be produced by changes in magnetic flux. Magnetic flux is a measure of the interaction with the magnetic field and is equal to BA times the angle between the field and the normal of the conductor. (A is the exposed area of the conductor)
Generators consist of electrical coils around rotating magnets. When the magnets rotate, the angle of the flux changes, causing electricity to occur. This type of electricity is alternating current.
Electrical motors are the exact opposite. They are electrical coils surrounding rotating magnets, but here the current rotates the magnet. Since alternating current has a changing magnetic field, it can constantly rotate a magnet.
Transformers
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Magnetic fields
Magnetic fields represent the direction of the force exerted by a magnet in a general area. Magnetic fields consist of field lines that typically extend from the north pole to the south.