11. Creating Magnets
The picture
shows that a
screwdriver does
not pick up paper
clips.
Methods used to create a magnet
12. Creating Magnets
Stroking using a permanent magnet
However, after
stroking the
screwdriver with a
magnet, the blade
itself becomes
magnetic and
attracts the paper
clips.
17. Laws of magnets shown
by flux lines
Unlike poles attract Like poles repel
18. Stray Lines of Force
Controlling stray lines using
a keeper
19. Magnetic Lines of Force
Notice how the
materials are affected
Soft iron is a material
that distorts flux
Magnetism will pass through any material
23. Electromagnets
A coil of wire can be made into a magnet by passing an
electric current through it.
Without electricity,
there is no
magnetic force
Electric current applied to a coil
creates a magnetic field
24. Electromagnetic Strength
Increase the number of coils.
Increase the electric current flowing
through
the coil.
Add an iron core in the center of the coil.
How can an electromagnet be made
stronger?
28. The magnet is strong
enough to lift this 50
pound engine cylinder
head.
The coil of wire has been
attached to a 12 volt DC
power source making an
extremely strong magnet.
Making a Magnet
29. Saturation
Saturation Knee
Y- Axis
Increasing
Magnetic
Force
Y
X- Axis Increasing Electric
Current
X
Saturation of a magnetic field occurs when an increase of
electric current flow does not increase the strength of the
magnetic field as shown by the graph. The knee of the
curve is the point that saturation occurs.
30. MAGNETIC COIL LOSSES
Copper losses - resistance of copper
coils.
Hysteresis - magnetic flux inducing a
current in the core.
Eddy currents - magnetic polarity of the
iron core is rapidly changed by an AC
current causing friction and heat
between the molecules
34. MAGNETIC TERMS
Flux - Invisible lines of force.
Poles - North and South where force is
strongest.
Permeability – The ability of a material to
conduct lines of force.
Residual Magnetism – The ability of a
material to hold its magnetism for a long
time.
35. MAGNETIC TERMS
Ferromagnetic Material – A material easy to
magnetize. (i.e., Iron Steel, Cobalt, Perm-alloy,
and Alnico)
Paramagnetic Material- A material that can be
slightly magnetized.
Diamagnetic Material – A material that is very
difficult to magnetize.
Magnetic Laws – Simply stated: Like poles
repel and unlike poles attract.
36. Review
What are the poles of a magnet?
Name the magnetic lines of force.
List five types of magnets and their two
families.
List the laws of magnets.
Explain two methods for making a magnet.
37. Review
Explain two theories of magnetism.
Name five different types of devices that are
associated with electromagnetism?
List three magnetic and three nonmagnetic
materials.
What will remove magnetic lines of force?
Editor's Notes
A natural magnet from the Earth known as a loadstone is attracting a paper clip
An type of magnet.
Other example material include: METALS, WOOD, PLASTIC, CERAMICS, RUBBER, GLASS, COMPOSIT FIBERS, AND ALL COMPOUNDS
An example of a very strong magnet made with a coil of wire and the flow of an electric current.