DOMAIN THEORY OF MAGNETISMSPH3U/SPH4C

TYPES OF MAGNETS Permanent

Temporary (materials that can be made magnetic but eventually lose their magnetic properties)

INDUCED MAGENTISM Materials containing IRON, NICKEL, or

COBALT can be magnetized when placed in/near a magnetic field.

FERROMAGNETISM Ferromagnetic Materials: these

materials include iron, nickel and cobalt (and alloys of these metals).

Two Types: Soft & Hard Ferromagnetic

Ex. Pure iron – remains magnetic only in the presence of a magnetic field.TEMPORARY Magnet

Ex. Steel (an alloy)– remains magnetic even after the magnetic field has been removed.SEMI-PERMANENT Magnet

MAGNETIC FIELD STRENGTH The magnetic field strength is a

fundamental force called the: Electromagnetic Force

It is incredibly strong … it is the second strongest force of the 4 fundamental forces.

Much, much stronger than the gravitational force.

DOMAIN THEORY OF MAGNETISM What is the theory of magnets?

Magnets have a North and South pole (N & S) All magnets are made of many smaller magnets called dipoles

(2 poles) Each dipole can interact with the other dipoles in the material,

if the dipoles line up in a single direction, then small magnetic domains are created; these act like tiny bar magnets

In a strong magnetic field all of the small magnetic domains line up forming one large magnet with N and S poles

Breaking a magnetic in two; domains remain aligned and two new magnets are formed.

Disrupting the alignment of the domains so that the dipoles are randomly distributed in demagnetization.

DOMAIN THEORY OF MAGNETISM Magnetic Domains UNALIGNED

Result: Not Magnetic overall

Regions or Domains

Individual Dipoles in a

domain

DOMAIN THEORY OF MAGNETISM Magnetic Domains ALIGNED

Result: Bar magnetic is formedIndividual Dipoles in a

domain

Regions or Domains

Regions or Domains

DOMAIN THEORY OF MAGNETISM Demagnetization: when you disorder

the alignment of the magnetic domains you will cause the material to not be magnetic overall. This can be done in 2 ways: Physically disrupt the alignment by

repeatedly striking the material Disrupt the alignment by heating the

material to a very high temperature.

DOMAIN THEORY OF MAGNETISM http://www.youtube.com/watch?

v=9KOLu9MxFq8

Need more help understanding the domain theory of magnetism? Watch the video on YouTube using the link above.