4 Fundamentals of Electricity: Unit 4 - Magnetism

Magnetic _____ _____ _____ repel each other and never cross.

lines of flux

A piece of _____ placed on a piece of wood floating in water, always aligns itself north and south.

lodestone (or magnatight)

In theory, each molecule of a _____ _____ is itself a small magnet.

magnetic material

The two factors that determine number of flux lines produced by an electromagnet are _____ and _____.

number of turns; amount of current

Like magnetic poles _____.

repel (Law of Magnetism or Law of Charges)

If the conductor is wound into a coil the magnetic lines of flux add to produce a _____ magnetic field.

stronger

The ____ electrons in a piece of iron account for its magnetic properties.

4

One of the best permanent magnet materials is _____.

Alnico 5

_____ _____ is a measure of a material's ability to retain magnetism.

Corrosive force of retentively or residual magnetism

_____ _____ are either metal or nonmetal materials that cannot be magnetized.

Diamagnetic materials

_____depend on electrical current flow to produce a magnetic field.

Electromagnets

Electricity was first discovered by the _____.

Greeks

In the CGS system of measurement, one magnetic line of force is known as a _____.

Maxwell

_____ _____ are magnets that do not require any power or force to maintain their field.

Permanent magnets

_____ is a measure of a material's ability to become magnetized.

Permeability

_____ is resistance to magnetism.

Reluctance

One Weber = _____ lines of flux.

a hundred million (10 to 8th power)

When a coil is wound around wood or plastic, it is known as an _____ _____.

air core

Opposite magnetic poles _____.

attract

In the _____ _____, the strange powers of the magnet were believed to be caused by evil spirits or the devil.

dark ages

The electron spin theory of magnetism is based on the theory of _____ _____ _____.

electron spin pattern

Magnetic lines of force are called _____.

flux

The reason that the _____ poles are called north and south is because the north pole of a compass needle points in the direction of the north _____ pole.

geographic; geographic

A magnet can be demagnetized with _____, _____, or _____.

heat, A/C magnetic field or striking it.

When a coil is wound around a magnetic material, it is called an _____ _____.

iron core