Download magnetism - bYTEBoss

MAGNETISM
N
S
MAGNETISM IS
PRODUCED BY MOVING
CHARGES.
MAGNETISM
TOPICS
S
N
Identifying magnetic materials
Magnetic poles
Magnetic materials
Magnetic fields
Electromagnets
MAGNETIC POLES
THE “N” POLE OF A MAGNET
MEANS THAT THIS POLE
SEEKS THE NORTH POLE OF
S
N
THE EARTH, IF THE MAGNET IS
FREE TO ALLIGN ITSELF WITH
THE EARTH’S MAGNETIC
FIELD.
LAWS OF ATTRACTION
LIKE POLES REPEL
N
S
N
S
N
S
UNLIKE POLES ATTRACT
N
S
N
S
MAGNETIC POLES
• A MAGNET IS A DIPOLE (TWO POLE).
• THERE IS NO MONOPOLE (SINGLE
POLE).
S
N
• CUT A MAGNET
IN HALF AND
YOU GET
TWO DIPOLES.
N
N
SN
S
MAGNETIC MATERIALS
• MOST MATERIALS ARE NOT MAGNETIC
• NATURALLY OCURRING MAGNETIC
MATERIALS ARE CALLED
FERROMAGNETIC
(IRON-LIKE)
S
N
• FERROMAGNETIC MATERIALS ARE
– IRON
– COBALT
– NICKLE
FERROMAGNETIC MATERIALS
The common metals, iron,
nickel and cobalt are
ferromagnetic.
ThereS are two
N
rare earth elements,
gadolinium and dysprosium
which also possess this
property.
Lodestone
N
• A Lodestone is a naturally
occurring piece of magnetic iron
oxide. It is often bound in a
brass frame, and is oriented to
place the magnetic poles at the
ends.
• The word magnet comes from
the region called Magnesia in
S word lodestone
Asia Minor. The
comes from the use of pieces of
ore from Norway and Sweden
which were suspended and
used as guiding or leading
stone; the Saxon word Læden
means "to lead".
FERROMAGNETISM
• ELECTRONS HAVE MAGNETIC FIELDS
DUE TO THEIR SPIN AND ORBITAL
MOTION.
• ATOMS OFNFERROMAGNETIC
S
MATERIALS POSSESS ELECTRONS
WHICH HAVE MAGNETICS FIELDS
THAT DO NOT CANCEL OUT INSIDE
THE ATOM.
MAGNETIC DOMAINS
N
S
THESE ARE SMALL REGIONS IN A
FERROMAGNETIC MATERIAL WHERE
ALL THE MAGNETIC FIELDS OF THE
ATOMS ARE ALIGNED.
MAGNETIZATION
N
S
N
S
IF THE DOMAINS ARE ALIGNED, THE
MATERIAL IS POLARIZED AND BECOMES
MAGNETIZED
MAKING A MAGNET
A PIECE OF SOFT IRON
CAN BE MAGNETIZED BY
N
RUBBING
ONE ENDS WITH
ONE POLE OF A STRONG
MAGNET.
MAGNETIC FIELD
• IMAGINARY LINES WHICH REPRESENT
THE ALIGNMENT OF A MAGNET
PLACED AT A POINT IN SPACE.
• AN ARROW CAN BE DRAWN AT A
POINT TO SHOW THE DIRECTION THAT
S
N
THE “N” POLE
POINTS
• IF THERE ARE A GREATER NUMBER
OF LINES IN AN AREA, THE FIELD IS
STRONGER THERE.
N
S
MAGNETIC FIELD
• MAGNETIC FIELD LINES POINT
TOWARDS THE “S” POLE.
• MAGNETIC FIELD LINES POINT
AWAY FROM
“N” POLES
S
N
N
S
EARTH’S MAGNETIC FIELD
SINCE A NORTH SEEKING
MAGNETIC POLE IS
ATTRACTED TOWARDS THE
S
N
EARTH’S MAGNETIC POLE
LOCATED NEAR GREENLAND,
THIS POLE MUST BE A
MAGNETIC SOUTH POLE.
EARTH’S MAGNETIC FIELD
NORTH POLE
S
S
N
N
SOUTH POLE
EARTH’S MAGNETIC FIELD
NORTH POLE
S
S
N
N
SOUTH POLE
MAGNETIC FIELD NEAR A
WIRE
THE FIELD NEAR A WIRE FORMS CIRCLES
AROUND THE WIRE.
N
S
MAGNETIC FIELD
ELECTRON FLOW
CHARGES MOVING IN CLOSED
PATHS CREATE DIPOLE
MAGNETIC FIELDS
N
S
FIELD DUE TO A COIL
CURRENT IN A COIL OF WIRE
PRODUCES AN ELECTROMAGNET
N
N
S
ELECTRON FLOW
S
ELECTROMAGNET
A STRONG ELECTROMAGNET CAN BE
PRODUCED BY USING A
FERROMAGNETIC CORE.
N
S