Transcript Magnets - HUNT for MCSHINSKY

Magnets
What is a magnet?
• A magnet is an object that has the
property of attracting certain
materials, mainly iron and steel.
North and South
• Every magnet has a
North Pole and a
South Pole.
• Opposite poles
attract (come
together) each
other.
• Like poles repel
(move away from)
each other.
• Attract - the act of
trying to come
together.
Natural Magnets
• A natural magnet
is an object which
has a magnetic
field around it. An
example of a
natural magnet is
Magnetite.
• The most popular legend
accounting for the discovery of
magnets is that of an elderly
Cretan shepherd named
Magnes. Legend has it that
Magnes was herding his sheep
in an area of Northern Greece
called Magnesia, about 4,000
years ago. Suddenly both, the
nails in his shoes and the
metal tip of his staff became
firmly stuck to the large, black
rock on which he was
standing. To find the source of
attraction he dug up the Earth
to find lodestones (load = lead
or attract). Lodestones contain
magnetite, a natural magnetic
material Fe3O4. This type of
rock was subsequently named
magnetite, after either
Magnesia or Magnes himself.
• Lodestones were used to tell
direction.
Magnetite
http://www.howmagnetswork.com/history.html
Permanent Magnets
• A permanent magnet is a
man-made object with a
magnetic field around it.
It has parts that are
usually labeled as North
and South. It will keep
its magnetism for a long
period of time.
• A permanent magnet can
be demagnetized by
heat, hammering and by
other magnets.
http://www.coolmagnetman.com/images/alnico2.jpg
Temporary Magnets
• A Temporary
Magnet is an
object which has
a magnetic field
around it for a
short period of
time. An example
of a temporary
magnet is an
electromagnet.
imanes
Imán natural
piedra imán
Ejemplos de imanes
naturales
magnetita
Imán permanente
Ejemplos de imanes
permanetes
herradura
barra
redondo
Imán temporal
Ejemplos de imanes
temporales
• electroiman
polo
• Polo: zona de un
imán donde el
campo magnético
tiene más fuerza
norte
sur
• Los imanes tienen
un polo norte y un
polo sur.
repeler
• Repelerapartar de sí
• Los polos
iguales se
repelen.
atraer
• Atraer- traer
hacia sí (jalar)
• Los polos
opuestos se
atraen.
Electromagnet
• A temporary
magnet made
by passing an
electric current
through a wire
coiled around
an iron bar.
Electromagnet
• A junkyard is one place to
see an electromagnet in
action. A crane holding a
huge electromagnet can be
used to pick up scrap metal
when current flows through
it. When the crane operator
wants to drop the scrap, he
or she will simply shut off the
current to the electromagnet.
http://www.bbc.co.uk/schools/ks3bitesize/science/physics/magnetism_5.sht
ml
Magnets have a magnetic field.
• A magnetic field
is the area around
a magnet where
you can detect
the force of the
magnet.
www.school-for-champions.com/science/images/magnetic_detection-iron_filings.jpg
Magnetic Field
• The magnetic
field is always
strongest near
the poles!
• If you cut a magnet
in half you will have
two new magnets.
They will both have
a North and a South
pole.
http://www.how-things-work-science-projects.com/second-gradescience-projects.html
Magnetic Force
• The power of a
magnet to push
or pull other
magnetic
material.
• The strength of
the magnetic field
is the magnetic
force.
Earth’s Magnetic Field
• The Earth does
not contain a
giant bar magnet,
but it behaves as
if it does. The
Earth has a
magnetic north
pole and a
magnetic south
pole.
http://www.bbc.co.uk/schools/ks3bitesize/science/physics/magnetism_5.sh
tml
We use Earth’s magnetic
field to figure out where
we are.
• A compass is an object
with a small magnetic
section that detects the
north pole of Earth and
points to it.
• the north pole of a bar
magnet is actually called
the 'north-seeking pole',
and it points to the
Earth's magnetic north
pole;
• the south pole of a bar
magnet is actually called
the 'south-seeking pole',
and it points to the
Earth's magnetic south
pole.
Compass
Where am I?
• The south pole of a magnet is attracted to the
Magnetic North Pole of the Earth. The south
pole of a bar magnet is labeled "N." This can
be confusing.
• A famous aviator nicknamed "Wrong Way
Corrigan" flew from New York to Ireland when
he was supposed to be going to Kansas. He
claimed he followed the wrong end of his
compass.
Magnets are everywhere,
can you think of where?
Magnetismo
• Magnetismo es
la fuerza de
atracción o de
repulsión de un
imán
Electroiman
• Imanes
temporarios
creados al pasar
una corriente
eléctrica a través
de un alambre
enroscado
alrededor de una
pieza de hierro
Campo magnético
• campo
magnético es el
espacio alrededor
de un imán
dentro del cual el
imán puede
atraer objetos
La tierra tiene un campo
magnetico.
Campo magnético fuerte
• La tierra tiene un
campo magnético
fuerte.
Campo magnético débil
• Un imán pequeño
tiene un campo
magnético débil.
Campo magnético
fuerte
Campo magnético
debil.
La brújula
• Usamos el campo
magnetico para
nevegar.