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Magnetism From Electricity. What electromagnets are and how they are important to our daily lives. What is a Maglev Train?. A train with no wheels Floats on a cushion of air Suspended by same-poled magnetic fields generated by a series of electro-magnets through the rail & the train. - PowerPoint PPT Presentation
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Magnetism From Electricity
What electromagnets are and how they are important to our daily
lives.
What is a Maglev Train?• A train with no wheels • Floats on a cushion of
air• Suspended by same-
poled magnetic fields generated by a series of electro-magnets through the rail & the train
Who is responsible for the discovery of Electromagnetism?
• Hans Christian Oersted• Found that a compass
was affected by a nearby electrified wire
• The compass needle moved differently depending on which direction the electricity flowed
What is Electromagnetism?
• The interaction between magnets and electricity
• Are useful for a large number of applications
• Can be controlled and manipulated
….more on electromagnetism.• By itself, the magnetic
field caused by electricity, is actually not strong enough to be very useful
• However electromagnets and solenoids can strengthen the magnetic field
What is a Solenoid?• A coil of wire that
produces a magnetic field when electric current passes through it
• The more loops = the stronger the magnetic field
• The magnetic field is very similar to a bar magnet’s magnetic field
Also the magnetic field increases with
increased current
What is an Electromagnet?• Made up of a solenoid
wrapped around an iron core
• The magnetic field (MF) aligns the domains in the iron core
• The MF is the combined MF of the coil and iron core
Can electromagnets be made stronger?
• Yes, by increasing the number of loops per meter (or per
centimeter) in the solenoid– Increasing the
number of loops around the iron core
• Remember Maglev trains?
Can electromagnets be turned off and on?
• Think about the practical applications of being able to start & stop magnetism
• A junk yard uses a huge electromagnet to pick up & drop tons of material!
What are some other practical uses of electromagnets?
• Doorbells • Electric locks• Circuit breakers• MRI machines
– Magnetic Resonance Imaging
• Speakers of any size• And many more
What is the relationship between magnetic force & electric current?
• If a current-carrying wire can cause a magnet to move…
• Then a magnet can cause a current-carrying wire to move
• This property is important in how electric motors work
What are electric motors?• A device that changes electrical energy into
mechanical energy• All electric motors have ….
– Armature - a loop or coil of wire that rotates– Armature is mounted between the poles of a permanent
magnet & electromagnet• Can use Direct Current (DC) - electricity moving in
one direction• Can use Alternating Current (AC) - electricity
moving in two directions
A Direct Current (DC) Electric Motor
A Direct Current (DC) Electric Motorcont…
What is a Galvanometer?
• Measures current• Can detect direction
of current • Useful in detecting
electrical polarity• Electricians use
instruments like this daily
Be sure to check the wikispace for more
information, a copy of this PowerPoint & website’s that
show details of electric motorshttps://nemsgoldeneagles.wikispaces.com/