What is
Magnetism???
Hmmm…
Magnetism – A force of
attraction and repulsion
Law of Magnetic Poles
Magnetic Field
N
S
Magnetic Domains
Demagnetizing a Magnet
1) Heating
2) Dropping
3) Other Strong Impact
Electricity and Magnetism
So, can an ordinary nail
become a magnet?
Wire
wrapped
around nail
Paperclips
attracted to
the nail
Electromagnet
Predicting the Factors Affecting Electromagnet
Strength
Increasing # Coils
Decreasing # Coils
Increasing Power
Decreasing Power
Increasing Core Diameter
Decreasing Core Diameter
Factors Affecting Electromagnet Strength
Battery
Strength
+ Iron
Nail with
40 Coils
9V
# Paper
Clips
# Coils +
Iron Nail
+ 6V
Battery
5
AA
10
C
25
6V
50
# Paper
Clips
Diameter
of Core +
40 Coils +
6V
Battery
# Paper
Clips
Generators
• Turns mechanical energy into electrical energy
A wire turns within a magnet creating an
electrical current
Which is stronger???
A
B
Which is stronger???
A
B
Part I –
Electromagnets and Communication
Today’s wireless communication devices – smart
phones, Ipods, email, etc. all owe their existance
to the invention of the telegraph in the 1830’s.
Using an electromagnet and wires connecting
the transmitter and receiver, messages could be
sent over long distances using Morse Code, a
system of communication long used with flags
and lights.
Today you will be constructing your own telegraph
system. You will be working together to construct
an electromagnet transmitter/receiver.
Look at the pictures and think about the material
you are provided. Be sure to think about what
materials conduct electricity and what materials are
magnetic. Then build your own
transmitter/receiver.
Part II –
Morse Code
Initially developed in 1836, Morse Code was used for
the transmission of words prior to the invention of
voice communication (i.e. telephone).
It is based on a series of dits (•) and dahs (-) based
on how often each letter occurs in English words.
Part II –
Morse Code
For many years, telegraph stations connection
railway station via wires and were used to transmit
information about train schedules, news, and “wire”
money.
Part II –
Morse Code
With the advent of wireless telegraphs, Morse
code also became the standard form of
communication between ships and airplanes,
replacing semaphore.
Part II –
Morse Code
After constructing your telegraph system, you will be
sending your partner a message using Morse code.
Write a message in English. Using the following code
key, translate the message to Morse code. Practice using
the transmitter until you are able to send your message.
Your partner will be receiving and decoding your
message. Your partner will then send you a message to
decode.
Morse Code