Transcript Electromagnets - cloudfront.net

ELECTROMAGNETS
REVIEW
• All matter has protons & electrons
• Electric current is the flow of charge through a material
• Amount of charge that passes through wire in a unit of time is rate of current
flow
RELATING ELECTRICITY TO
MAGNETS
• Electric current creates magnetic field
• Any electrical charge in motion creates magnetic field
• Direction of current determines direction of magnetic field
• Reverse current, magnetic field reverses
• Can control a magnetic field by using an electric current
SOLENOIDS
• Current carrying coil of wire with many loops
• Creates magnetic field that can be turned on & off by switching the current
on & off
USES OF ELECTROMAGNETS
• Lifting heavy pieces of scrap metal
• Recording information on audiotapes, videotapes, computer disks, or credit
cards
• Talk into a microphone, the vibrations of your voice are change into an electric
current
• Current is used in an electromagnet in the recoding head of the tape recorder
to produce magnetic field
WAYS TO INCREASE STRENGTH OF
ELECTROMAGNET
• Increase current in the solenoid
• Add more loops of the wire
• Wind the coils closer together
• Using stronger ferromagnetic material as core
• https://www.youtube.com/watch?v=emlzh9XXWgQ
HOW TO GET ELECTRICITY TO
YOUR HOUSE
• http://www.childrensuniversity.manchester.ac.uk/interactives/science/energ
y/electricity/
ASSESSMENT!
• The region in which magnetic forces act is called a
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Line of force
Pole
Magnetic field
Field of attraction
• An example of a ferromagnetic material is
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Plastic
Wood
Copper
iron
• The person who first suggested that Earth behaves as a magnet was
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Ampere
Oersted
Gilbert
Columbus
• The region in which Earth’s magnetic field is found is called the
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Atmosphere
Stratosphere
Aurora
magnetosphere
• A coil of current-carrying wire with an iron core is called
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Ferromagnet
Electromagnet
Compass
Maglev
TRUE OR FALSE
• If false, replace the underlined word to make it true 
• Like poles of magnets repel each other
• The type of magnetic mineral found in nature is called platinum
• A compass needle points in the direction of Earth’s geographic north pole
• You can increase the strength of an electromagnet by adding more turns of
a wire to it
• Explain why you are not left with one north pole and one south pole if you
break a magnet in half.
• How does a material become magnetic?
• How does Earth act like a magnet?
• What is an aurora? How is it produced?
• Why does a compass needle change direction when it is placed near a
current-carrying wire?
• The created magnetic field interferes with Earth’s magnetic field