chapter 4 basic electrical

A basic law of magnetism states that unlike poles _____ and like poles _____.

attract; repel

The angular difference between true north and magnetic north is known as the angle of _____.

declination

Of the three basic classifications of magnetic materials, _______________ materials are either metal or nonmetal materials that cannot be magnetized.

diamagnetic

Magnetic lines of force are referred to as _____.

flux

In the English system of measure, magnetic strength is measured in terms of _____.

flux density

If a permanent magnet is cut into pieces, each piece _____ a separate magnet.

is

To locate the north pole of an electromagnet, use the _____-hand rule.

left

What type of magnets do not require any power or force to maintain their field?

permanent magnets

Of the three basic classifications of magnetic materials, _______________ materials are metals that are most easily magnetized.

Ferromagnetic

The three substances that form natural magnets are _____.

diron,nickel, and cobalt

The regions formed in the molecular structure of magnetic metals are sometimes called magnetic _____.

domains

Earth contains magnetic poles.

true

The north pole of a compass needle points in the direction of the south geographic pole.

true

Man-made permanent magnets retain their magnetism _____ than natural magnets.

longer

In the English system, the total force producing a magnetic field is the _____.

maganetomotive force

The strength of an electromagnet is primarily proportional to its _____.

ampere-turns

If an object is placed in the field of an strong electromagnet connected to an AC line, the object will be _____.

demagnetized

Magnetism can be explained in terms of _____ spin patterns.

electron

Lodestone is a name for a naturally occurring magnetic material that is also called _____.

magnetite

When a magnetic material's molecules are all lined up, and increases in current flow no longer cause increases in magnetic field strength, the material has reached _____.

saturation

What type of magnet depends on flowing current to produce a magnetic field?

electromagnet

The measure of a material's ability to be magnetized is called _____.

permeability

The measure of a material's resistance to magnetism is known as _____.

reluctance

The amount of magnetism left in a material after the magnetizing force has stopped is called _____.

residual magnetism

The north magnetic pole of a compass needle is attracted to the _____ magnetic pole of the earth.

south