RT 209 Topic 3 (Magnetism)

Magnetism

The force where objects are attracted or repelled to one another; it is considered one of the fundamental forces, is difficult to detect or measure, and has no smallest units

Magnet

Any material that produces a magnetic field

Bipolar/Dipolar

Refers to magnets that have two poles

Poles

The ends of a magnet

Magnetic Dipole

Groups of atoms with most of the magnetic moment force in a single or same direction

Magnetic Domain

An accumulation of many atomic magnets with their dipoles aligned

Magnetic Permeability

The ability of a material to attract the lines of a magnetic field density or absorb magnetic flux

Natural Magnet

Magnets that occur in nature, such as the Earth

Artificial Permanent Magnet

Strong magnetic fields that do not fade, typically made of hard steel in the shape of a bar or horseshoe, such as a compass

Electromagnets

Temporary magnets produced by means of an electric current running through coils of wire usually wrapped around an iron core

Non-magnets/Diamagnets

Materials that are unaffected when brought into a magnetic field and do not retain magnetic properties when the field is removed, such as wood, glass, and plastic

Ferromagnets

Materials with a large, positive susceptibility to an external magnetic field that can retain magnetic properties after the field is removed and exhibit strong attraction, such as iron and alnico

Paramagnets

Materials that lie between ferromagnets and diamagnets and do not retain magnetic properties when an external field is removed, such as gadolinium

Magnetic Susceptibility

The degree to which a material can be magnetized or its ability to become magnetized by an external magnetic field

First Magnetic Law

Every magnet, no matter how small, has two poles: north and south

Second Magnetic Law

Like magnetic poles repel and unlike magnetic poles attract

Third Magnetic Law

Ferromagnetic material can be made magnetic when placed in an external magnetic field

Fourth Magnetic Law

The force between poles is proportional to the product of the magnetic pole strengths divided by the square of the distance between them

Tesla

The SI unit of magnetic field strength

Gauss

An older unit of magnetic field strength, where one tesla equals 10,000 gauss

Electromagnetism

The force associated with electrons in motion

Alessandro Volta

The individual associated with the voltaic pile

Hans Oersted

The scientist who demonstrated that electricity can generate magnetic fields and that any charged particle in motion induces a magnetic field

Solenoid

A coil of wire

Michael Faraday

The scientist who observed current in a changing magnetic field and described the first law of electromagnetic induction

Faraday’s Law

The principle that electric current will be induced to flow in a circuit if some part of that circuit is in a changing magnetic field

Heinrich Lenz

The scientist who established the law regarding the direction of induced current

Lenz’ Law

The principle that induced current flows in a direction such that it opposes the action that induced it

Self-induction

The induction of an opposing electromotive force (EMF) in a single coil by its own changing magnetic field

Mutual induction

The process of inducing a current flow through a secondary coil

Electric Generator

A device that changes mechanical energy into electrical energy by placing a coil of wire in a strong magnetic field between two poles

Electric Motor

A device that changes electrical energy into mechanical energy

Direct Current Motor

A motor where energy is supplied to a series of wire loops

Induction Motor

A motor where energy is supplied to the external magnet