Download Electromagnetism

Electromagnetism
Magnetism from Electricity
1. Electric current can produce a
magnetic field and the direction of
that field depends on the direction of
the current.
Solenoids
2. Magnetic fields can be increased by increasing
the amount of current. A solenoid is a coil of
wire that produces a magnetic field when
carrying an electric current.
How to increase magnetic field in a
solenoid
• a. more loops = larger magnetic field
• b. more current = larger magnetic
field
Electromagnetic
Electromagnets consists of a solenoid wrapped
around an iron core.
a. The field produced by the solenoid causes
the domains inside the iron core to become
aligned making it stronger than a regular
solenoid.
b. Electromagnets can be turned off and on.
c. You can additionally make the
electromagnetic stronger by
increasing loops, the size of the core
or the current in the wire.
d. Strong electromagnets can lift
trains!
Magnetic Force & Electric Current
Not only can an electric current cause magnets
to move but
Magnets can cause electric current to move!
Transformers
A transformer increases or decreases the voltage
of alternating current.
Often located on top of electrical poles to
decrease voltage before it goes in to your
home.
Applications of Electromagnetism
Doorbells – doorbells contain a solenoid with an
iron rod inserted part way. The current is
controlled by the button. Press the button
and a switch in the solenoid circuit closes.
The magnetic field that is created pushes the
rod into the bell.
Electric Motors
An electric motor is a device that changes
electrical energy into kinetic energy. The
motor uses magnets to create motion. The
electrical current enters into the motor to the
commutator which turns the armature a half
turn, current is reversed which turns the
armature another half turn until it spins.
Electricity from Magnets
Electromagnetic induction is when electric
current is produced by changing a magnetic
field.
Applications
Generators use electromagnetic induction to
convert kinetic energy to electrical energy. A
coil of wire is placed between the poles of a
permanent magnetic. As the crank is turned
the coil cuts through the magnetic field lines
and induces an electric current in the wire.