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REVIEWER SA science 10 (Second Quarter)
Magnets
Magnet
A substance that possesses magnetic properties.
Poles
The two ends of a magnet
Every magnet has two poles: South pole (S), and
North pole (N).
Even you break the magnet in half, each half will
have a North and South pole.
Properties of
Magnets
Force of Repulsion - Like magnetic poles repel
each other
Force of Attraction Unlike magnetic poles
attract each other
Ferromagnetic
A substance like iron, and steel are strongly
attracted to magnets, these substances are called
Ferromagnetic.
Nickel and Cobalt are also Ferromagnetic. These
materials are often called magnetic materials.
Paramagnetic
Some substances, such as wood, Aluminum,
Platinum, and Oxygen are just slightly attracted
by strong magnets.
Diamagnetic
Substances that are slightly repelled by magnets.
Examples: Table Salt, Mercury, Zinc, and Gold
diamagnetic substances.
Magnetite
(Permanent Magnet)
Substances that are already magnetized.
These are called natural or permanent magnets
Lodestones are permanent magnets.
Artificial Magnets
Materials that can be made into magnets.
Artificial Magnets are made by induced magnetism.
ALNICO Magnet
A permanent magnet containing ALuminum, NIckel,
and CObalt.
Temporary Magnets
Temporary Magnets are those of soft iron that are
easy to magnetize and loses their magnetic
property very easily.
Uses of Magnets
Five Elements that
can be made into
Magnets
Iron, Cobalt, Nickel, Aluminum, Gadolimium, and
Dysprosium.
Alloy
Mixture of 2 or more metals.
Steel
Classic Material for making a permanent magnet.
An alloy of Carbon and iron.
Magnequench
The best materials for permanent magnets
Which was invented in 1985
This material is mostly iron, with a little
Neodymium and Boron added.
Magnetic Domains
Clusters of many atoms, can be thought of as tiny
magnets.
Atoms themselves have magnetic properties due to
the spin of atom’s electrons. Group of atoms join
so that their magnetic fields are all going in
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the same directions. These areas of atoms are
called “domains”.
When an unmagnetized substance is placed in a
magnetic field the substances can become
magnetized this happens when spinning electrons
line up in the same direction.
Before: When the material is unmagnetized, the
domains are not lined up in a definite way. There
are randomly arranged.
After: When the material is magnetized, the
domains lined up in a define patterns. All the
north poles point in one direction and the south
poles in the other.
Magnetic Field
The region around the magnet where it has a
magnetic effect is called its magnetic field.
When a magnetic material is placed in a magnetic
field it will experience a force.
The iron fillings feel the effect of the magnetic
field and line up along the direction of the
forces in this region.
Magnetic Force
Electric Charges exert electrostatic forces of
attraction and repulsion on each other while they
are at rest.
When the charges are in motion, they still exert
electrostatic forces along with magnetic forces.
Magnetic Field of a Magnet
Bar Magnet
In general, the iron filings that align along the
magnetic field lines concentrate most near the
poles. The lines from one pole flow outside a
magnet or a paramagnetic source and enters the
other end, going back inside the magnet to form
close loops generally referred to as lines of
force.
Like poles
(Bar Magnet)
The magnetic Field pattern between two North
poles of bar magnets resemble the magnetic field
pattern between two south poles of two bar
magnets. Lines from one pole bend away from the
lines flowing out or flowing into the other pole.
Unlike poles
(Bar Magnet)
If the two bar magnets with two unlike poles
which are closed in between is brought together,
the magnetic field pattern will resemble that of
the single bar magnet. Lines from one pole enter
the other pole.
Latch or
Refrigerator Magnet
The latch or refrigerator magnet has parallel
alternating magnetic field bands. The dark bands
of concentrated iron filings are wider than the
bands almost.
U-Shaped Magnet
The magnetic field pattern between the poles of a
U-shaped magnet resembles the field pattern
between unlike poles of two bar magnets.
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Disk Magnet and
Neodymium Magnet
Because of the neodymium’s strength, it pulls
more iron filings towards it, pulling even those
that are already far, making a region where the
forces between magnetically induced iron filings
are weaker than the neodymium magnet’s pull on
them. Thus, there is a space without iron filings
anymore.
Both the Disk magnet and the Neodymium magnet
have Radial Magnetic field lines. The iron
filings surrounding radially the disk magnet is
less concentrated than the radial magnetic field
lines surrounding the Neodymium Magnet which is
many times stronger.
Iron nail wrapped
with current
carrying wire
(-+)
The magnetic Field patterns of an electromagnetic
nail, a current carrying straight conductor, and
a current carrying coil are similar to that of
the single bar magnet.
Straight Current-
Carrying Wire
(-+)
The magnetic Field patterns of an electromagnetic
nail, a current carrying straight conductor, and
a current carrying coil are similar to that of
the single bar magnet.
Current-Carrying
Coil
(-+)
The magnetic Field patterns of an electromagnetic
nail, a current carrying straight conductor, and
a current carrying coil are similar to that of
the single bar magnet.
Electromagnetism: Relationship Between Electricity and Magnetism
Convectional flow of
Current
From positive terminal to negative terminal. (of
the source or the battery)
Hans Christian
Øersted
On the morning of February 16,1820, an important
discovery was made by accident. Professor Hans
Christian Øersted in Denmark was giving a lecture
on electricity. He closed a switch to demonstrate
the flow of current. There happened to be a
compass hereby. Every time he closed the switch,
the compass needle turned. He discovered by a
magnetic field.
Investigating the
Current of Magnetism
In 1819, Hans Christian Øersted noticed that when
he connected a battery to a circuit, a nearby
compass was deflected from magnetic north.
Stage 1.- A simple circuit is setup with one of
the connecting wires passing through a small hole
in a piece of card
Stage 2.- move the small plotting compass around
the card to investigate the magnetic field
produced by wire.
Stage 3.- A concentric circle in a circular
motion of field lines was formed. (clockwise or
counterclockwise).
Magnetic Induction
The process by which the screws become magnets is
called Magnetic Induction. This same process is
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