1. Magnetic Force
What is magnetic force and what causes it to happen in a material?
How do magnets work?
What are poles in magnets?
How do magnetic poles repel and attract each other?
What are some objects that a magnet will attract?
What are some objects that a magnet will not attract?
How are electromagnets made and used?
2. What is magnetic energy and what causes it to happen in a
material?
Magnetism is the invisible force where objects are attracted or repelled to one another.
Usually these objects are metals such as iron. Magnetism acts between objects that are
apart or touching.
Magnetism is contained inside the atoms that make up a material. When the electrons
and protons inside the atoms of a material become aligned in a certain way, polarity is
created. Then the material will have magnetic force.
Magnetism can only be created in a material. Depending on strength of the magnet,
objects that enter the area around it may become magnetic, also. This area around a
magnet is called its magnetic field.
3. What materials are magnetic?
Some minerals, or the rocks that contain
them, are naturally magnetic. Iron,
lodestone, nickel, and cobalt are some
examples.
Some materials are always magnetic, like
those in refrigerator magnets.
Other materials can be magnetized by
being near a magnet. The nails on the
lodestone above are also magnetized.
Electricity can be used to create magnets,
called electromagnets.
4. What are poles in magnets?
The magnetic force surrounding a magnet
is not the same throughout the magnet.
The force is concentrated at the ends of
the magnet, not in the middle.
You can prove this fact by dipping a
magnet into iron filings, as shown these
pictures. Many filings will cling to the ends
of the magnet, while very few will stick to
the center.
The two ends, which are the regions of
concentrated lines of force, are called the
poles of the magnet. Magnets have two
magnetic poles. Both poles have equal
magnetic strength.
5. How do magnetic poles repel and attract each other?
At the poles of a magnet, the magnetic strength is most powerful. These poles are
called north and south. The poles are called this because, when a magnet is
suspended, the magnet will line up in a north - south direction. (This occurs because
of the polarity of the Earth, which is really a giant magnet! Earth’s magnetic north is
near the North Pole. This is why a compass works, too.)
6. How do magnetic poles repel and attract each other?
Opposite poles attract; similar poles repel.
N-N, S-S = no attraction: When the north pole of one magnet is placed near the north
pole of another magnet, the poles are repelled. When the south poles of two magnets
are placed near one another, they also are repelled from one another.
N-S, S-N = attraction: When the north and south poles of two magnets are placed
near one another, they are attracted to one another.
The strength of the attraction or repulsion of two magnets towards one another
depends on how close they are to each other and how strong the magnetic force is
within the magnet. The further apart the magnets are, the less they are attracted or
repelled to one another. The weaker the magnets are, the less they are attracted or
repelled to one another.
7. What are some objects that a What are some objects that a
magnet will attract? magnet will not attract?
nails wood
other magnets (NS not SS or NN) most types of stone
iron objects rubber
steel objects cotton cloth
lodestone wool
nickel objects sandstone
Can you think of others?
8. How are electromagnets made and used?
Magnets called electromagnets can also be made using electricity. A simple
electromagnet is formed with a battery and copper wire coiled around a metal rod
such as a nail. Adding electricity magnetizes the nail and creates a magnetic field
around it.
9. How are electromagnets made and used?
Electromagnets must be connected to a battery or other source of electricity to work .
Unconnected electromagnet. Connected electromagnet
attracting many iron filings
