Magnetism and Matter (Ch

The long and interesting hismagnetism...

Pre HistoryPre-History• Stone Age – Tools were m• Bronze Age (3500 to 1100– Sn alloy)y)• Iron Age (1200 to 600 BC

Ancient History• Thales of Miletus (624 – 5(iron ores from Magnesia informs of iron ore are hemat

Middle AgesFe2Og

• Lodestones were used to m(Europe or China?) WilliamMagnete in the year 1600.

19th Century• Michael Faraday found thdiamagnetic (1845).

Lectu

hap. 9)

story of the science of

made of stone0 BC) – Tools of bronze (Cu

C) – Tools of iron (Fe)

546 BC) described a force in )n Greece; the two main tite and magnetite.

O3 Fe3O4

magnetize compass needles. m Gilbert published De

hat most materials are

ure 9.1

DemoLodestone and compass need

We will study three kinds of ma

Ferromagnetism• Fe, Co, Ni; some alloys• Microscopic domains have• A macroscopic sample of • A macroscopic sample of have a permanent magnetiza

Paramagnetism• Placed in a magnetic field• Placed in a magnetic field,magnetization in the same d• A paramagnetic material imagnet pole.g p

Diamagnetism• Placed in a magnetic field,magnetization in the directiog• A diamagnetic material is magnet pole.

(Th t th (There are two other, more sin matter: antiferromagnetis

Lectu

agnetism

e nonzero magnetization.ferromagnetic material may ferromagnetic material may ation.

the material has , the material has direction as B.is attracted (weakly) to a

, the material has on opposite to B.pp repelled (weakly) from a

btl ki d f ti subtle, kinds of magnetism sm and ferrimagnetism.)

ure 9.1

Lectuure 9.1

Lectuure 9.1

Lectuure 9.1

Lectuure 9.1

ParamagnetismParamagnetism

♦ The atoms of the materiadipole moment m, even whenBut the dipoles point in rand

♦ When a magnetic field is partially with the field so mpartially with the field, so mthem toward alignment.

SectioEquati

♦ Note that the susceptibilitt i l i i t l material is approximately pr

Lectu

al have a permanent magnetic n there is no applied field. dom directions so m = 0.

applied, the dipoles align m B The torque twistsm B. The torque twists

on 9.1ion 9.6

ty of a paramagnetic ti l t 1/Troportional to 1/T.

ure 9.1

Diamagnetism

♦ The atoms of the materiamagnetic dipole moment. Thatapplied field.

♦ When a magnetic field is a magnetic moment in the dmagnetic field – an induced dg

♦ Why?

S tiSectioEquati

♦ Note that the susceptibilit♦ Note t at t e suscept b tmaterial is approximately in

Lectu

al have no permanent t is, m = 0 when there is no

applied, the atom develops direction opposite to the dipole moment.p

9 1on 9.1ion 9.5

ty of a diamagnetic ty o a d a ag et c ndependent of temperature.

ure 9.1 1

Lectu 1ure 9.1