Download Permanent Magnet

MAGNETISM, IT’S SO
ATTRACTIVE!!
A magnet is an object
that attracts (brings near)
minerals/metals such as iron,
nickel, cobalt and steel. The
ends of a magnet are called
poles. A magnet has a north
pole and a south pole.
Opposite poles attract; the
north pole of one magnet
attracts the south pole of
another magnet. Like poles
repel (move away from); the
north pole of one magnet
pushes away the north pole
of another magnet.
Properties/qualities/
characteristics of a magnet:
Polarity
Magnetic Field
Repel
Attract
Their ability to react to electrical
charges
What are some common uses for magnets?
Did you name some?
Magnets are everywhere
WHAT ARE MAGNETS?
Permanent Magnet: An object that keeps its magnetism after it has been
magnetized.
These are the most common type of magnets that we know and interact with in our daily
lives. The magnets on our refrigerators. These magnets are permanent in the sense that
once they have been magnetized they retain a certain degree of magnetism. Permanent
magnets are generally made of ferromagnetic material. ( Ferro means iron, and its origin
is from Italy.) Such material consists of atoms and molecules that each have a magnetic
field and are positioned to reinforce each other.
Temporary Magnet: A magnet that does not keep its magnetism.
Temporary magnets are those that simply act like permanent magnets when they are
within a strong magnetic field. Unlike permanent magnets however, they loose their
magnetism when the field disappears. Paperclips, iron nails and other similar items
are examples of temporary magnets. Temporary magnets are used in telephones and
electric motors amongst other things.
Types of Magnets
NATURAL MAGNET:
SUBSTANCES MADE OF AN
IRON MATERIAL THAT IS
NATURALLY MAGNETIZED
BY THE EARTH’S MAGNETIC
FIELD. MAGNETITE OR
LODESTONES
History of Magnets
Compass: an instrument used to determine geographic direction on
Earth.
Shape & Configuration
Permanent magnets can be made into
any shape imaginable. They can be
made into round bars, rectangles,
horseshoes, donuts, rings, disks and other
custom shapes. While the shape of the
magnet is important aesthetically and
sometimes for experimentation, how the
magnet is magnetized is equally
important. For example: A ring magnet
can be magnetized S on the inside and
N on the outside, or N on one edge and
S on the other, or N on the top side and
S on the bottom. Depending on the end
usage, the shape and configuration vary.
Rod Magnet
Horse Shoe Magnet
Types of Magnets
U-shape Magnet
Cow Magnet
Domino
Magnet
Disc Magnet
Ring
Magnets
Certain metals are attracted to magnets:
Iron, Nickel, and Cobalt
The swirling flow of molten
iron and nickel around Earth's
solid center triggers an
electrical current, which
generates the planet's
magnetic field. Remember the
Earth’s magnetic field goes
from pole to pole, the same
shape as a bar magnets field.
Magnetic force:
Attract
the push or pull of a magnet on another
magnetic material.
(draw together)
(Push apart)
Repel
MAGNETIC FIELD
THE MAGNETIC FORCE THAT EXISTS AROUND A MAGNET
A compass tells you what direction
is 'North', but have you ever
wondered how it can do that? The
answer has to do with something
called magnetism. Every magnet
produces an invisible area of
influence around itself. When things
made of metal or other magnets
come close to this region of space,
they feel a pull or a push from the
magnet. Scientists call these
invisible influences FIELDS. You can
make magnetic fields visible to the
eye by using iron chips sprinkled on
a piece of paper with a magnet
underneath.
Polarity
MAGNETIC FIELD OF VARIOUS TYPES
OF MAGNETS:
EARTH’S MAGNETIC FIELD
The magnetic field of Earth is caused by currents of electricity that flow in the
molten core. These currents are hundreds of miles wide and flow at thousands of
miles per hour as the earth rotates. The powerful magnetic field passes out through
the core of the earth, passes through the crust and enters space. This picture was
created by a computer from a mathematical model, shows the solid inner core
region (inner circle) surrounded by a molten outer core (the area between the two
circles). The currents flow in the outer core, and the lines of force shown in yellow,
travel outwards through the rest of Earth's interior. If the earth rotated faster, it
would have a stronger magnetic field. If it had a larger liquid core it would also
have a stronger magnetic field. By the time the field has reached the surface of
earth, it has weakened a lot, but it is still strong enough to keep your compass
needles pointed towards one of its poles.
Neato Magneto
Electromagnetism is magnetism that is produced when an electric current
passes through a wire coiled around an iron core.
Electromagnets
Superconductors
These are the strongest magnets. They don't need a metal core at all, but are made of
coils of wire made from special metal alloys which become superconductors when cooled
to very low temperatures.
Make your own electromagnet
ELECTROMAGNETISM
Permanent Magnets compared to Electromagnets
Always have a magnetic
field, hence permanent
No electric current
needed.
Fixed magnetic strength
Permanent magnet loses
its magnetic properties, as
it does by heating to a
high temperature, it will
be rendered useless for
ever.
Flow of Electric Current
Creates a
magnetic
field.
Used for the
benefit of
man.
The magnetic field
ceases with an on/off
switch.
Made from a coil of
wire and an electric
power source.
An electro magnet runs on
electricity
strength of an electromagnet
can be adjusted by the amount
of electric current that flows.
EFFECTS OF MAGNETS ON THE NEEDLE
OF A COMPASS
Magnets effect the needle only at close distances. Magnets close to a
compass overrides the Earth’s effect on the needle.
Point the Way
Compass: an instrument used to determine geographic direction on
Earth.
EFFECTS OF EARTH’S MAGNETIC FIELD
ON THE NEEDLE OF A COMPASS
The Earth’s magnetic field effects the needle at great distances.
Where Am I really?
REAL-WORLD APPLICATION
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MRI and other uses of magnets in the medical field.
When would you want a metal not to be a magnet?
Mechanics use for magnets, how would this be useful?
Magnets are now being used to clean fish tanks. How?
How do hikers use a compass and a map?
How do pilots use a compass to navigate?
Compare and contrast life on the North and South Poles.
What does the saying, “opposites attract” mean?
Discuss how high-speed trains in Japan and Germany use magnets to operate.
The trains are magnetically propelled across the tracks at a very high speed of
up to 500km per hour.
10. Miss Valora uses a magnet in her summer job in Alaska.
11. Where do we see electromagnets in use in our daily lives?
12. Iron in our diet, is it important? What are other ways for scientists to separate
mixtures besides using magnets?
Reading Comprehension Review
Research and Report