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Electricity and Magnetism
Science Posse
University of Wyoming
What is ELECTROMAGNETISM?
 The fundamental relationship between electric
fields and magnetic fields
Electromagnetism
 A moving electric field creates a magnetic field
that rotates around it
 A moving magnetic field creates an electric field
that rotates around it
 The Right Hand Rule helps describe this
The Right Hand Rule
 First define positive electric current as flowing
from the positive (+) end of a battery, through
an electric circuit, and back into the negative (-)
end.
 Next define a magnetic field as always pointing
away from a North pole and towards a South
pole.
The Right Hand Rule
 Curl your fingers in the direction of the rotating
field.
 Extend your thumb. It now points in the direction
of the other field.
 If your fingers are curling along with a rotating
electric field, your thumb will point in the
direction of the magnetic field and vice versa.
The Right Hand Rule
The Electromagnet
 By the Right Hand Rule, a coil of wire with
current flowing in it will create a magnetic field
 The strength of the magnetic field depends on
 The amount of current in a wire – More current
means stronger magnetic field
 The number of turns in the coil – More turns
means stronger magnetic field
 The material in the coil – Magnetic materials like
iron and steel make the magnetic field stronger
The Electromagnet
 A simple electromagnet can be made by coiling some wire
around a steel nail, and connecting a battery to it.
 As current rotates around the nail, a magnetic field is created
with the North pole at the bottom and the South pole at the
top
The Electromagnet
 Electromagnets are found in many everyday
objects such as
 Motors and generators
 Doorbells
 Speakers
 Hard drives
 VHS and Audio cassette tapes
 Telephones
The Electric Motor
 An electric motor is a device that converts
electromagnetic energy into mechanical energy
 It works by using special electromagnets in the
case of the motor that create North and South
poles that are constantly spinning in a circle.
 These spinning poles pull along magnets that are
on the rotor (the part that spins), causing it to
rotate
The Electric Generator
 An electric generator works in the opposite of
a motor; it converts mechanical energy into
electromagnetic energy
 An outside force moves magnets in a circle past
several coils of wire.
 By the Right Hand Rule, electric currents are
developed in the coils of wire.