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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.
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MAGNETISM –THE ABILITY OF CERTAIN MATERIALS TO ATTRACT IRON, COBALT OR NICKEL.
CLASSIFICATION OF MAGNETS • NATURAL MAGNETS • ARTIFICIAL PERMANENT MAGNETS • ELECTROMAGNET
LODESTONES BECAME MAGNETIZED BY LYING IN THE EARTH’S MAGNETIC FIELD FOR THOUSANDS OF YEARS
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
The magnetic compass was brought to Europe in the Middle Ages from the Chinese who had been using the compass for over 1500 years MAGNETIC COMPASS
ALNICO—ALLOY OF: • AL—ALUMINIUM • NI—NICKEL • CO—COBALT
ELECTROMAGNETS TEMPORARY MAGNETS PRODUCED BY MEANS OF ELECTRIC CURRENT.
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)
LIKE MAGNETIC POLES REPELEACH OTHERUNLIKE 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
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
AN ELECTRIC CHARGE SPINNING ON ITS AXIS WILL CREATE 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
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
IN NONMAGNETIC MATERIALS JUST AS MANY ELECTRONS SPIN IN ONE DIRECTION AS IN OTHER.THEIR OPPOSING MAGNETIC FIELDS CANCEL OUT NUCLEUS
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 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 PERMEABILITY EASE WITH WHICH A GIVEN MATERIAL CAN BE MAGNETIZED