Magnetism From Electricity What electromagnets are and how they are important to our daily lives.
Feb 23, 2016
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/