Download Electromagnetism

ELECTROMAGNETISM
Section 1: What is Electromagnetism?
WHAT IS ELECTROMAGNETISM?
 (1820)
Hans Christian Oersted produced a
current in a wire during a lecture.
 When he brought a compass near the wire, the
compass changed direction.
 Whenever he turned on the current in the
wire, the compass needles lined up around the
write in the shape of a circle.
ELECTRIC CURRENT & MAGNETISM
 How

A
can you observe electromagnetism?
Compass & electric current
compass needle normally points north
because it aligns itself with Earth’s magnetic
field
 The needles of compasses surrounding a
current will align with the current, producing
a circle
ELECTRIC CURRENT & MAGNETISM
Wherever
there is electricity, there is
magnetism
An electric current produces a magnetic
field
This relationship is called
electromagnetism
WHAT DO THEY LOOK LIKE?

An electromagnets can be made out of a variety
of materials but they all have the following:
Voltage source (battery or other source)
 A magnetic core
 Wire wrapped around the
core. This is known as a
solenoid. The more times
the wire is wrapped around
the core the greater the
strength of the magnet.

THE MAGNETIC FIELD

The magnetic field produced by a current
has three distinct characteristics:
1. The field can be turned on and off
2. The field can have its direction reversed
3. The field can have its strength changed
THE MAGNETIC FIELD
 You
can turn a magnetic field produced by
a current on and off…
 How can you turn the magnetic field off?
 Simply by turning the current off!
THE MAGNETIC FIELD
 You
can change the direction of a
magnetic field…
 How can you change the direction?
 Simply by reversing the direction of
the current!
SOLENOIDS
 You
can change the strength of a magnetic
field produced by a current…
 How can you change the strength?


A
Simply by looping, or winding, the wire of the wire!
The strength will increase as the number of loops or
coils increases
solenoid is a coil of wire with a current.
ELECTROMAGNETS
A
solenoid with a ferromagnetic core is called
an electromagnet.
 The magnetic field of an electromagnet can be
hundreds or thousands of times stronger than
the magnetic field of the current alone
 Basically, an electromagnet is a strong magnet
that can be turned on or off.
ELECTROMAGNETS

You can increase the strength of an
electromagnetic field…
1.
2.
3.
4.
Increase the current in the solenoid
Add more loops of wire to the solenoid
Wind the coils of the solenoid closer together
Increase the strength of an electromagnet by
using a stronger ferromagnetic material for the
core
COMMON ELECTROMAGNETS
 Audiotapes
 Videotapes
 Computer
hard drives
 Credit cards
 Doorbells
 Radios
 Refrigerators