What is Magnetism???Hmmm…

Magnetism – A force of attraction and repulsion

Law of Magnetic Poles

N S

Magnetic Field

Magnetic Domains

Demagnetizing a Magnet

1) Heating

2) Dropping

3) Other Strong Impact

Electricity and Magnetism

?

So, can an ordinary nail become a magnet?

Nail

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

# Paper Clips

# Coils + Iron Nail

+ 6V Battery

# Paper Clips

Diameter of Core + 40 Coils +

6 V Battery

# Paper Clips

9 V 5

AA 10

C 25

6 V 50

Generators• Turns mechanical energy into electrical energy

A wire turns within a magnet creating an electrical current

Which is stronger???

A B

A B

Which is stronger???

http://www.youtube.com/watch?v=kp3hY3r4yUg

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.

http://www.youtube.com/watch?v=Lki3jxNLVCI

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