Electrical Systems

# Introduction to Magnetism 211

Introduction to Magnetism provides a thorough overview of magnetism and how it relates to electricity. Magnetism is a force of attraction and repulsion that occurs when the molecules in a material align. Materials become magnetized when they are exposed to a magnetic field. Materials can be demagnetized with heat, vibration, or a magnetic field generated by alternating current. Magnets have two different poles, like the earth. Magnetic forces exit the north pole of a magnet and are attracted to the south pole. These forces, or lines of flux, are essential for producing electricity with magnetic induction.

Electricity and magnetism are closely related. Magnetism is used to create electricity, and electricity is used to create magnetism. Most of the world’s electricity comes from magnetic induction. Understanding how these and other magnetic devices work requires familiarity with magnetism and its relationship to electricity.

• Difficulty Intermediate

• Format Online

• Number of Lessons 15

• Language English

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Course Outline
• Magnetism
• Magnetic Domains
• Magnetic Properties
• Magnetic Classifications
• Magnetizing
• Demagnetizing
• Magnets and Magnetization Review
• Poles and Polarity
• Magnetic Lines of Flux
• Electricity and Magnetism
• Polarity, Flux, and Electricity Review
• Electromagnets
• Magnetic Induction
• Uses of Magnetic Induction
• Final Review
Objectives
• Define magnetism.
• Describe magnetic domains.
• Describe magnetic properties.
• Describe the main magnetic classifications.
• Explain how to magnetize materials.
• Explain how to demagnetize materials.
• Describe polarity.
• Describe magnetic lines of flux.
• Describe how magnetism relates to electricity.
• Describe electromagnets.
• Describe magnetic induction.
• Describe uses of magnetic induction.
Glossary
Vocabulary Term
Definition

alloys

A uniform mixture of two or more materials. Alloys consist of at least one metal.

alternating current

AC. Electricity that reverses direction at regularly recurring intervals of time. Alternating current switches direction 60 times per second, or 60 hertz, in the U.S.

aluminum

A lightweight silver-white metallic element that is diamagnetic. Aluminum is essentially non-magnetic.

axis

An imaginary straight line that passes through the center of an object. An axis has a pole on each end.

brass

An alloy of copper and zinc that is diamagnetic. Brass is essentially non-magnetic.

carbon

A common nonmetallic element that exists in several forms. Carbon is added to iron to form steel.

cobalt

A brittle silver-white metallic element that is ferromagnetic. Cobalt is one of the few naturally magnetic metals.

compass

A tool for determining geographic direction that uses a magnetic needle as a pointer. A compass' needle points to the earth's north geographic pole.

conductor

A material or element that allows free movement of electrons and therefore allows easy flow of electricity. Conductors are typically metals.

demagnetize

To eliminate a material's magnetism. To demagnetize a material, disrupt the regular pattern of aligned magnetic domains.

diamagnetic

A material or substance that is not magnetic. Diamagnetic materials include brass and aluminum.

direct current

DC. Electricity that travels in one direction. Direct current does not reverse the direction of flow, unlike alternating current.

electricity

A form of energy created by the movement of electrons. Electricity can be converted into light, heat, or motion.

electromagnet

A magnet that gains an attractive force only when current passes through it. Electromagnets are extremely powerful.

electrons

A negatively charged particle that orbits the nucleus of an atom. Electrons flowing between atoms causes electricity.

ferromagnetic

A material or substance that is highly magnetic. Ferromagnetic materials include iron, cobalt, nickel, and manganese.

generators

A device that converts mechanical energy into electrical energy. Generators operate on the principle of magnetic induction.

geographic poles

The opposite ends of the earth's rotational axis. The geographic poles are located at the northernmost and southernmost points of the earth.

hydroelectric plant

An electricity-generating facility that uses water to create power. Hydroelectric plants use magnetic induction to produce electricity from the mechanical motion of water.

induces

Generates. Magnets induce current in a conductor.

insulator

A material that disrupts, inhibits, or prevents the transmission of sources of energy such as heat, light, and sound. Insulators include rubber and plastic.

iron

A strong silver-gray metallic element that is ferromagnetic. Iron is one of the few naturally magnetic metals.

magnet

A metallic object or substance that possesses a force that attracts or repels other metals. Magnets attract opposite charges and repel like charges.

magnetic axis

The imaginary line connecting the north and south poles of a magnet. The magnetic axis of the earth connects the earth's magnetic poles.

magnetic domain

A group of atoms that have been aligned in parallel to the magnetic north and south. The amount of aligned magnetic domains determines a material's magnetism.

magnetic field

The area in and around a magnet in which a magnetic force exists. Magnetic fields exhibit the powers of attraction and repulsion.

magnetic flux

The force that surrounds a magnet and exhibits the powers of attraction and repulsion. Magnetic flux is described as imaginary lines of force that exit the magnet's north pole and return to its south pole.

magnetic induction

The use of magnets to cause voltage in a conductor. Magnetic induction occurs whenever a conductor passes through magnetic lines of flux.

magnetic poles

The opposite ends of the earth’s magnetic axis. The magnetic poles's locations shift slightly over time due to changes in the earth's magnetic field.

magnetism

The power of attraction and repulsion that exists in materials. Magnetism most often occurs between metals.

magnetize

To make a material magnetic or attractive to other metals. To magnetize a material, align its magnetic domains.

manganese

A brittle grayish-white metallic element that is ferromagnetic. Manganese can be made highly magnetic, but it is not naturally magnetic.

molecules

A pair or group of atoms that are chemically bound together. Molecules in magnetic materials line up in parallel.

motors

A machine that converts one form of energy, such as electricity, into mechanical energy or motion. Motors operate on the principle of magnetic induction.

nickel

A malleable silver-white metallic element that is ferromagnetic. Nickel is one of the few naturally magnetic metals.

northern hemisphere

The half of the earth that lies above the equator. The northern hemisphere includes the earth's north geographic pole.

parallel

Two lines or axes that are equidistant from one another at all points. Parallel lines do not intersect.

paramagnetic

A material that is not naturally magnetic but that can be made magnetic with some effort. Paramagnetic materials include platinum and titanium.

permanent magnet

A magnet that retains its attractive force after it is removed from a magnetic field. Permanent magnets have high residual magnetism.

permeability

A material's tendency to become magnetized. Permeability is the opposite of reluctance.

platinum

A precious grayish-white metallic element that is paramagnetic. Platinum can be slightly magnetized with some effort.

polarity

A state of opposites. Polarity determines the north and south attractions of a magnet and the positive and negative charges in a circuit.

poles

Opposite ends of an axis. Poles also refer to the opposite ends of a magnet.

reluctance

A material's resistance to becoming magnetized. Reluctance is the opposite of permeability.

residual magnetism

The attractive force that exists in an object or substance after it has been removed from a magnetic field. Residual magnetism is a characteristic of permanent magnets.

rotational axis

The center line on which a ball or sphere turns or rotates. The rotational axis of the earth connects the earth's geographic poles.

saturation

A magnetic state in which the attractive strength of a magnet has reached its peak. Saturation indicates that all of a material's molecules are aligned.

southern hemisphere

The half of the earth that lies below the equator. The southern hemisphere includes the earth's south geographic pole.

steel

An alloy of iron and carbon that is ferromagnetic. Steel is the most common manufacturing metal.

surface grinder

A grinding machine used to finish flat surfaces or grind parts to accurate size. Surface grinders often use electromagnets as workholding devices.

titanium

A strong low-density metallic element that is paramagnetic. Titanium can be slightly magnetized with some effort.

workholding device

A device used to locate and hold a workpiece. Workholding devices often use electromagnets.