MAGNETISM

MAGNETISM –THE ABILITY OF CERTAIN MATERIALS TO ATTRACT IRON, COBALT OR NICKEL.

CLASSIFICATION OF MAGNETS NATURAL MAGNETS ARTIFICIAL PERMANENT MAGNETS ELECTROMAGNET

NATURAL MAGNET -EARTH

NATURAL MAGNETS--LODESTONES

LODESTONES BECAME MAGNETIZED BY LYING IN THE EARTH’S MAGNETIC FIELD FOR THOUSANDS OF YEARS

THE SPHERE OF ARCHIMEDES THE ANCIENT GREEKS RECOGNIZED THE MAGNETISM OF LODESTONES MORE THAN 2500 YEARS AGO THE SPHERE OF ARCHIMEDES

ARTIFICIAL PERMANENT MAGNETS HARD STEEL MAGNETIC COMPASS ALNICO

HARD STEEL—HORSHOE MAGNET

MAGNETIC COMPASS The magnetic compass was brought to Europe in the Middle Ages from the Chinese who had been using the compass for over 1500 years

ALNICO—ALLOY OF: AL—ALUMINIUM NI—NICKEL CO—COBALT

ALUMINUM CAN NOT BE MAGNETIZED

ALNICO—SUPER STRONG MAGNETS

ELECTROMAGNETS TEMPORARY MAGNETS PRODUCED BY MEANS OF ELECTRIC CURRENT.

ELECTROMAGNET

MRI ELECTROMAGNET

LAWS OF MAGNETISM EVERY MAGNET HAS TWO POLES LIKE MAGNETIC POLES REPEL: UNLIKE POLES ATTRACT THE FORCE OF ATTRACTION OR REPULSION FOLLOWS INVERSE SQUARE LAW ( NOT ACCURATE)

EVERY MAGNET HAS TWO POLES- NORTH & SOUTH

LIKE MAGNETIC POLES REPELEACH OTHER UNLIKE POLES ATTRACT EACH OTHER

THE FORCE OF ATTRACTION OR REPULSION BETWEEN TWO MAGNETS Pp F = k d2 THE FORCE IS PROPORTIONAL TO THE PRODUCT OF THE MAGNETIC POLE STRENGTHS DIVIDED BY THE SQUARE OF THE DISTANCE BETWEEN THEM

NATURE OF MAGNETISM

BREAKING A MAGNET WILL RESULT IN EACH FRAGMENT BECOMING A WHOLE MAGNET

HEATING OR HAMERING STEEL IN PROXIMITY TO A MAGNET –WILL MAGNETIZE IT. STROKING OF IRON WITH MAGNET WILL MAGNETIZE IT GENTLY JARRING A TEST TUBE OF IRON FILINGS NEAR A MAGNET WILL MAGNETIZE IT

MAGNETIZATION

AN ELECTRIC CHARGE SPINNING ON ITS AXIS WILL CREATE MAGNETIC FIELD

MOVING CHARGED PARTICLE WILL INDUCE MAGNETIC FIELD

THE SMALL MAGNET CREATED BY ELECTRON ORBIT IS CALLED A MAGNETIC DIPOLE

ACCUMULATION OF MANY ATOMIC MAGNETS WITH THEIR DIPOLES ALIGNED CREATES A MAGNETIC DOMAIN

THE MAGNETIC DIPOLES IN BAR MAGNET GENERATE IMAGINARY LINES OF THE MAGNETIC FIELD

MAGNETIC LINES OF FORCE ARE CLOSE LOOPS

MAGNETIC LINES OF FORCE EARTH

MAGNETIC LINES OF FORCE BAR MAGNET

THE STRENGTH OF MAGNETIC FIELD IS EXPRESSED IN SI UNIT TESLA 1 TESLA = 10,000 GAUSSES

MAGNETIC ELEMENT TWO OR MORE ELECTRONS SPINNING IN THE SAME DIRECTION NUCLEUS

A MAGNETIC ELEMENT CAN EXISTS EITHER IN MAGNETIZED OR NON-MAGNETIZED STATE

MAGNETIZED MAGNETIC MATERIAL

NON-MAGNETIZED MAGNETIC MATERIAL

IN NONMAGNETIC MATERIALS JUST AS MANY ELECTRONS SPIN IN ONE DIRECTION AS IN OTHER. THEIR OPPOSING MAGNETIC FIELDS CANCEL OUT NUCLEUS

AURORA BOREALIS

CHARACTERISTICS OF THE LINES OF FORCE FROM NORTH TO SOUTH OUSIDE THE MAGNET IN THE SPACE FROM SOUTH TO NORTH INSIDE THE MAGNET IF IN THE SAME DIRECTION THEY WILL REPEL MAGNETIC FIELD IS DISTORTED BY MAGNETIC MATERIALS BUT NOT AFFECTED BY NON-MAGNETIC MATERIALS

LINES OF FORCE

LINES OF FORCE REPEL N S N S

LINES OF FORCE ATTRACT S N N S

NONMAGNETIC MATERIALS DO NOT AFFECT THE LINES OF FORCE OF MAGNETIC FIELD

MAGNETIC MATERIALS LIKE IRONAFFECT THE LINES OF FORCE

MAGNETIC INDUCTION (MAGNETIZATION)

MAGNETIZATION –DOMAINS MOVE

MAGNETIC PERMEABILITY EASE WITH WHICH A GIVEN MATERIAL CAN BE MAGNETIZED

MATERIAL RESISTANCE TO MAGNETIZATION MAGNETIC RETENTIVITY MATERIAL RESISTANCE TO MAGNETIZATION

SOFT IRON HIGH PERMEABILITY LOW RETENTIVITY

HARD STEEL LOW PERMEABILITY HIGH RETENTIVITY

“EASY COME—EASY GO”

MAGNETIC CLASSIFICATION OF MATTER FERROMAGNETIC PARAMAGNETIC MATERIALS NONMAGNETIC MATERIALS DIAMAGNETIC MATERIALS

FERROMAGNETIC MATERIALS –IRON, COBALT, NICKEL FERROMAGNETIC MATERIALS –IRON, COBALT, NICKEL. STRONGLY ATTRACTED BY MAGNETS

PARAMAGNETIC MATERIALS—PLATINUM. FEEBLY ATTRACTED BY MAGNETS

NONMAGNETIC MATERIALS—COPPER, WOOD, GLASS NONMAGNETIC MATERIALS—COPPER, WOOD, GLASS. THEY ARE NOT ATTRACTED TO MAGNETS.

DIAMAGNETIC MATERIALS—BERYLLIUM & BISMUTH. FEEBLY REPELLED BY MAGNETS

DETECTION OF MAGNETISM ---COMPASS GEOGRAPHIC NORTH POLE IS MAGNETIC SOUTH POLE????? S. MAGNETIC N. GEOGRAPHIC S. GEOGRAPHIC N. MAGNETIC

SMALL MAGNETS