Agenda 5/18
• Circular Motion Warm-Up
• Hand back GA Packets
• Demo: Disney Mythbusters
• Notes: Magnets
• Conclusion: In-class Mythbusters
Disney Mythbuster
• https://www.youtub
e.com/watch?v=HF
rCkt60A9w
It this really possible?
• Could Pluto
swallow a magnet
and still be able to
pick up all kinds of
metal things?
• What do you think?
• Why or why not?
Magnetism
• The physics behind magnets parallel the
physics behind charge very well.
Electric Charges vs Magnets
• Positive & negative
charges
• Like charges repel
• Opposite charges attract
• Electric Fields surround
electric charges
• Can isolate a charge
• North (seeking) &
south (seeking) poles
• Like poles repel
• Opposite poles attract
• Magnetic fields
surround magnets
• Cannot isolate a pole
Different Types of Magnets
• Magnets come in
many shapes and
sizes. (bar magnets,
circular magnets,
horseshoe, etc.)
• No matter what the
shape or size every
magnet must have a
north and south pole.
What happens if you break a
magnet in half?
N
S
N
S
N
S
N
S
• If you break a magnet in half, each side will still
have a north pole and a south pole.
• If you continued breaking the magnet into smaller
and smaller pieces every piece will have a north
pole and a south pole.
More on Breaking Magnets
• This picture further
shows what happens
when a magnet gets
broken in half.
• Breaking magnets can
be purchased but we
believe it works better
to “fake” it.
Agenda 5/19/15
• Warm-Up
• Finish Notes: Magnetism
• Electromagnets Activity
– Paper clip activity
Magnetic Domains
• This diagram represents an
unmagnetized iron nail.
The arrows represent the
alignments of the magnetic
domains. These domains
are not aligned.
• This diagram represents a
bar magnet. The domains
in the magnet are aligned.
How Does Something Become
Magnetized?
• If you touch the nail to the bar magnet, the nail becomes
magnetized.
• This is because the domains in the nail will now align.
• If you remove the nail, the domains fall back out of
alignment and the nail loses its magnetism.
Magnetic Fields
• A magnetic field can be
thought of as a field that
shows magnetic force
lines.
• You can easily show the
magnetic field with iron
filings and a magnet. The
iron filings will line up
with the magnetic field.
• Out of the South into the
North
The Earth’s Magnetic Field
• The north pole of a compass
seeks north because is aligns
with the Earth’s magnetic field.
• What gets a bit confusing is the
magnetic south is in the
geographic north and vice versa.
• Scientists believe that the
Earth’s magnetic field comes
from convection currents in the
liquid outer core.
Agenda 5/20/15
• Warm-Up
• Breakdown Electromagnets
– Demo Electromagnets
• Complete Magnetic Fields
• 2nd Period: Research for Mouse Trap Car
Electromagnets
• Benefits:
– Can be turned on and off by switch
– Can be adjusted depending on use of magnet
• Drawbacks:
– Must have a current supply
– Potential for dangerous situations
• Fires, shorted circuits
Electromagnet Applications
• Motors
• Crane
• Projectiles
Magnetic Field Lines
• Which direction do the run??
Bar Magnet
Horseshoe Magnet
Ring Magnet
Problems
N
S
S
N
Problems
N
N
S
S
Agenda 5/22
• Two Tasks Today:
1. Complete the construction of your
mousetrap car
2. Complete your semester 2 review guide
– Cheat Sheet/Formula Sheet Allowed