magnetism

how is magnetism exhibited

occur when charged particles are in motion

magnetic domain

accumulation of many atomic magnets

what do the circles represent

magnetic field around moving charge

non-magnetized state

domains in random arrangement

• example is iron

magnetized state

domains align with a N to S orientation

magnetism units

tesla (T)

classification of magnets

natural, artificial permanent, electromagnets

nature magnet

found in nature that include magnetites that exhibit magnetism

• examples include earth, iodestone, iron oxide

artificial permanent magnet

man made that include hardened steel, alloy, and compasses

electromagnets

temporary magnets created by a current of electron and iron core

current vs. magnetic field relationship

stronger current = greater magnetic field

magnetic permeability (suscepitibility)

ease with which material can be magnetized

magnetic retentivity

ability of a material to hold magnetization

permeability vs. retentivity relationship

inverse relationship

• increased susceptibility while decreased retentivity

• decreased susceptibility while increased retentivity

magnetic classification of matter

ferromagnetic, paramagnetic, diamagnetic, nonmagnetic

ferromagnetic

materials that can be magnetized and exhibit strong magnetic properties

• strongly attracted to a magnet

paramagnetic

materials that are weakly attracted to a magnetic field

• loosely influenced by a magnetic field

diamagnetic

materials that are weakly repelled by a magnetic field and cannot be magnetized

• not attracted to a magnet

• examples are elements in the periodic table

nonmagnetic

materials unaffected by a magnetic field

magnetic force field direction

form a closed loop

• N to S outside the magnet

• S to N inside the magnet

what do field lines pass through

both magnetic and non-magnetic materials

what are field lines concentrated by

magnetic materials

what are field lines unaffected by

non-magnetic materials

magnetism law #1

every magnet has two poles designated by N & S that cannot be separated

magnetism law #2

like poles repel, unlike poles attract

magnetism law #3

force between two magnetic poles varies directly as the strength of the poles and inversely as the square distance of the distance between poles

strength of magnetism

determined by # of field lines per unit area

two ways to create a magnet

• stroking an iron bar repeatedly with a magnet

  • hammering a piece of iron in the presence of a magnet